BoP Lab / Buttonwillow Raceway Park

HP vs P vs SM vs GTX pace at Buttonwillow Raceway Park

Quickest here: HP 2:03.082 Lee Fleming, Cal Club 2025 race · P 1:32.872 Jim Devenport, Cal Club 2025 qualifying · SM 2:00.831 William Wallis, Cal Club 2025 qualifying · GTX 1:49.596 Rob Scholl, Cal Club 2025 race

Lap times% of HP

HPPSMGTXsolid race · dashed qualifying · slower is lower

HPPSMGTXsolid race · dashed qualifying · each class's best lap as a share of HP's at the same event (the reference class, changeable above); 100% is level, higher is quicker

	Event	HP			P					SM					GTX
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs HP	% of HP	Qual best	Race best	Trap	vs HP	% of HP	Qual best	Race best	Trap	vs HP	% of HP
	Cal Club 2026 CALCL262026-02-21	2:04.965Brian Linn · fastest of 3 · top 3 within 4.8s-1.805s (-1.42%)	2:03.324Lee Fleming · fastest of 3 · top 3 within 0.9s+0.242s (+0.20%)	126.2Lee Fleming+25.8 mph (+25.7%)	1:38.716Kevin Mitz · fastest of 3 · top 3 within 3.1s+5.844s (+6.29%)	1:37.287John Manfroy · fastest of 3 · top 3 within 3.5s+3.315s (+3.53%)	160.4John Manfroy+18.7 mph (+13.2%)	-26.037squal -26.249s	78.9%qual 79.0%	2:01.392Ryan Busk · fastest of 18 · top 5 within 0.8s+0.561s (+0.46%)	2:02.486William Rasmussen · fastest of 18 · top 5 within 1.3s+0.836s (+0.69%)	127.3Sam Rezai+23.4 mph (+22.6%)	-0.838squal -3.573s	99.3%qual 97.1%	1:54.892Moze Cowper · only car	1:55.330Moze Cowper · only car+5.734s (+5.23%)	146.0Moze Cowper+29.6 mph (+25.4%)	-7.994squal -10.073s	93.5%qual 91.9%
41 rule changes (HP: 29, P: 6, SM: 3, GTX: 3)9 weight · 7 engine · 6 cars added · 4 induction · 1 suspension & brakes · 1 tyres & wheels · 13 wording · HP Triumph Spitfire 1296cc compression ratio increases from 11.0 to 12.0:1. · GTX Misc Table 4 adds RCR T70 Coupe with 2200 lbs minimum weight, no restrictor specified. · HP Toyota MR-2 1.6L (85-89) compression ratio set to 11.0:1. · BMW 2002 newly classified to H Production at 2350 lbs with 1990cc iron block, 40 DCNF carburetor, 11.0:1 compression. · Prototype carbon-carbon and carbon-ceramic brake rotors now permitted instead of prohibited. · Datsun SPL-311 newly classified to HP at 2050 lbs with 1595cc OHV iron engine and specified carburetors. · EP Triumph TR2-TR4A allows 5-speed gearbox without overdrive; removes Weber carb and weight specification. · EP BMW Z3 2.5L restrictor reduced 52mm to 50mm, weight increased to 2550 lbs base; five other BMW models get smaller restrictors. · HP Honda Civic and CRX models get wider 13-inch wheels: 6 to 7 inches. · EP Nissan 280Z minimum weight reduced from 2560 to 2400 lbs. · EP Mazda MX-5 1.8L 90-97 weight reduced to 2125 lbs from 2150 lbs. · HP Austin-Healey Sprite/Midget 1098cc minimum weight drops 80 lbs to 1550. · HP Volvo 142/142E gains compression ratio limit 12.0:1 and valve lift limit .425". · HP Mini Cooper 07-15 valve lift reduced to .390", from .450". · FP and HP Volkswagen Rabbit descriptions updated: Convertible changed to Cabriolet in FP; Cabriolet added to three HP engine variants. · EP, FP, HP: rear drum brake to disc conversion clarified; rotors solid, diameter limited to largest front rotor permitted. · EP Ford Mustang (94-98) fuel injected throttle body inside diameter specified at 60. · HP Plymouth Arrow transmission max speeds clarified to 4 or 5. · EP, FP, HP wheel diameter added to Appendix G as absolute maximum specification. · EP, FP, HP throttle body inside dimensions must remain stock with +/-.25mm tolerance; butterfly dimensions stock in FP, HP only. · P class 13B rotary engine restrictor changes to 40mm SIR fuel injection or 41.5mm venturi carburetor. · Prototype class adds Radical SR3 spec line to Table 1 effective 9/1/25. · Prototype P2 cars may now run P2 spec or modified Prototype spec in Prototype class; clarified language and added Radical Cup series table. · Prototype Engine Table A 2-cycle restrictor reduces from 40mm to 38mm venturi size. · EP BMW Z4 03-05 restricted to 52mm flat plate intake restrictor. · EP Fiat 124 Spider 1600 & 2000 weight drops 50 lbs to 2000; carburetors gain 2mm chokes to 36mm. · GTX Ligier LMP3 now allows any normally aspirated LS Chevrolet engine. · HP Fiat X-1/9 base weights reduced 50–53 lbs across 1300 and 1500 spec lines. · SMX drivers must submit data acquisition files on time or face suspension and $250 fine. · SMX penalty language clarified: level 1 and 3 infractions may carry $1,000 fine; level 2 and 4 may carry $500 fine. · GTX Porsche GT2 RS Clubsport classified with factory specifications required at all race events. · Class P adds clarification notes on restrictor requirements, throttle bodies, Mazda 12A engine spec, and P2 auto-based engine rules. · SM cars limited to one set of Hoosier SM 7.5 P205/50/ZR17 per Super Tour event weekend for dry sessions. · Chevrolet Spark 16-22 classified HP Pre at 1850 lbs minimum weight, fuel injected, 1399 cc. · HP Ford Festiva 88-93 minimum weight drops to 1600 lbs, variants to 1640 and 1680 lbs; compression ratio raised to 11.0:1. · EP BMW Z3 and 3-series models get smaller intake restrictors: Z3 2.5L to 52mm, Z3 2.8L to 55mm, 328i to 58mm, 325i to 56mm. · HP Mazda 2 11-14 base weight up 50 lbs to 2045; all VW 80s models up 50 lbs to 2150 base. · EP, FP, HP: interior or exterior mirrors meeting rule 9.3.36 now permitted. · EP Honda S2000 1997cc base loses 75 lbs to 2375; 2157cc base loses 60 lbs to 2450. · EP Mazda MX-5/Miata 99-05 minimum weight drops to 2100 lbs, 2153 lbs with power adder, 2205 lbs with two adders. · HP Mini Cooper 07-13 engine corrected to DOHC; valve lift limit reduced to 0.390 inches.showhide 2026-02-01 HP Triumph Spitfire 1296cc Compression Ratio Increase to 12:1 #39589enginefasterHP Triumph Spitfire 1296cc compression ratio increases from 11.0 to 12.0:1. 2026-01-01 GTX Please Consider Adding a Spec Line to GTX Table 4 for the RCR T70 #39470cars addedneutralGTX Misc Table 4 adds RCR T70 Coupe with 2200 lbs minimum weight, no restrictor specified. 2026-01-01 HP E/O: Improve Consistency of the Spec Lines #39500engineunclearHP Toyota MR-2 1.6L (85-89) compression ratio set to 11.0:1. 2026-01-01 HP Request to Reclassify BMW 2002 Into H Production #39567cars addedneutralBMW 2002 newly classified to H Production at 2350 lbs with 1990cc iron block, 40 DCNF carburetor, 11.0:1 compression. 2026-01-01 P Request to Continue to Allow Carbon Brakes #39476suspension & brakesneutralPrototype carbon-carbon and carbon-ceramic brake rotors now permitted instead of prohibited. 2025-12-01 HP Request to Re-Classsify Datsun SPL-311 to HP from FP #39116cars addedneutralDatsun SPL-311 newly classified to HP at 2050 lbs with 1595cc OHV iron engine and specified carburetors. 2025-12-01 HP TR2 Notes E&O #39180wordingunclearEP Triumph TR2-TR4A allows 5-speed gearbox without overdrive; removes Weber carb and weight specification. 2025-12-01 HP Balance of Power #39187induction +50 lbsslowerEP BMW Z3 2.5L restrictor reduced 52mm to 50mm, weight increased to 2550 lbs base; five other BMW models get smaller restrictors. 2025-12-01 HP Alternative BOP Request for 84-87 Honda CRX/Civic #39223tyres & wheelsfasterHP Honda Civic and CRX models get wider 13-inch wheels: 6 to 7 inches. 2025-11-01 HP Please Lower Weight of 280Z #38871weight -160 lbsfasterEP Nissan 280Z minimum weight reduced from 2560 to 2400 lbs. 2025-11-01 HP Miata Weight Adjustment Follow Up #38949weight -25 lbsfasterEP Mazda MX-5 1.8L 90-97 weight reduced to 2125 lbs from 2150 lbs. 2025-11-01 HP Weight Break for 1098 Midget / Sprite #38970weight -80 lbsfasterHP Austin-Healey Sprite/Midget 1098cc minimum weight drops 80 lbs to 1550. 2025-11-01 HP HP Volvo 142 spec omission #38994engineslowerHP Volvo 142/142E gains compression ratio limit 12.0:1 and valve lift limit .425". 2025-11-01 HP HP Mini DOHC 1.6 #38996engineslowerHP Mini Cooper 07-15 valve lift reduced to .390", from .450". 2025-11-01 HP Add to Rabbit description #39019wordingneutralFP and HP Volkswagen Rabbit descriptions updated: Convertible changed to Cabriolet in FP; Cabriolet added to three HP engine variants. 2025-11-01 HP Clean-up 9.1.5.E.7e #39025wordingneutralEP, FP, HP: rear drum brake to disc conversion clarified; rotors solid, diameter limited to largest front rotor permitted. 2025-11-01 HP Add TB size to Ford Mustang (94-98) Spec Line #39130wordingneutralEP Ford Mustang (94-98) fuel injected throttle body inside diameter specified at 60. 2025-10-01 HP HP Plymouth Arrow spec omission #38995wordingneutralHP Plymouth Arrow transmission max speeds clarified to 4 or 5. 2025-10-01 HP Add Wheel Diameter to Appendix G #39008wordingneutralEP, FP, HP wheel diameter added to Appendix G as absolute maximum specification. 2025-10-01 HP Add TB ID tolerance to general Prod rules #39009wordingneutralEP, FP, HP throttle body inside dimensions must remain stock with +/-.25mm tolerance; butterfly dimensions stock in FP, HP only. 2025-09-01 P 13B Rotary Engine Rules Change Request #38856engineunclearP class 13B rotary engine restrictor changes to 40mm SIR fuel injection or 41.5mm venturi carburetor. 2025-09-01 P Add Radical Cup series Radical SR3 spec line to Table 1 #38916cars addedneutralPrototype class adds Radical SR3 spec line to Table 1 effective 9/1/25. 2025-09-01 P Clarify spec line cars language #38943wordingneutralPrototype P2 cars may now run P2 spec or modified Prototype spec in Prototype class; clarified language and added Radical Cup series table. 2025-08-01 P RM 25-05 - Prototype Engine Table A, 2 Cycle Restrictor Change #38929inductionslowerPrototype Engine Table A 2-cycle restrictor reduces from 40mm to 38mm venturi size. 2025-07-01 HP BMW Z4 update #38490inductionslowerEP BMW Z4 03-05 restricted to 52mm flat plate intake restrictor. 2025-07-01 HP EP Fiat 124 Spider Competition Adjustment Request #38498weight -50 lbsfasterEP Fiat 124 Spider 1600 & 2000 weight drops 50 lbs to 2000; carburetors gain 2mm chokes to 36mm. 2025-06-01 GTX Ligier P3 LS Swap #38164engineunclearGTX Ligier LMP3 now allows any normally aspirated LS Chevrolet engine. 2025-06-01 HP Base Weight Adjustment for H-Production X1/9 Spec Lines #38255weight -50 lbsfasterHP Fiat X-1/9 base weights reduced 50–53 lbs across 1300 and 1500 spec lines. 2025-06-01 SM SMX Data Submission - Penalties #38248wordingneutralSMX drivers must submit data acquisition files on time or face suspension and $250 fine. 2025-06-01 SM Committee) SMX Penaly Clarification updated language #38337wordingneutralSMX penalty language clarified: level 1 and 3 infractions may carry $1,000 fine; level 2 and 4 may carry $500 fine. 2025-05-01 GTX Request to Classify Porsche GT2 RS Clubsport #37972cars addedneutralGTX Porsche GT2 RS Clubsport classified with factory specifications required at all race events. 2025-05-01 P Add missing punctuation marks #38150wordingneutralClass P adds clarification notes on restrictor requirements, throttle bodies, Mazda 12A engine spec, and P2 auto-based engine rules. 2025-05-01 SM Clarify Tire Marking Regs #38005wordingneutralSM cars limited to one set of Hoosier SM 7.5 P205/50/ZR17 per Super Tour event weekend for dry sessions. 2025-04-01 HP Request for Classification of Chevrolet Spark #37755cars addedneutralChevrolet Spark 16-22 classified HP Pre at 1850 lbs minimum weight, fuel injected, 1399 cc. 2025-04-01 HP Request to Lower Ford Festiva Minimum Weight to 1600 LBS #37939weight -100 lbsfasterHP Ford Festiva 88-93 minimum weight drops to 1600 lbs, variants to 1640 and 1680 lbs; compression ratio raised to 11.0:1. 2025-03-01 HP Request Competition Adjustment to BMW Z3 2.5L #37120inductionslowerEP BMW Z3 and 3-series models get smaller intake restrictors: Z3 2.5L to 52mm, Z3 2.8L to 55mm, 328i to 58mm, 325i to 56mm. 2025-03-01 HP HP Class Adjustments #37459weight +50 lbsslowerHP Mazda 2 11-14 base weight up 50 lbs to 2045; all VW 80s models up 50 lbs to 2150 base. 2025-03-01 HP Interpretation of Production Rules on Mirrors #37235wordingneutralEP, FP, HP: interior or exterior mirrors meeting rule 9.3.36 now permitted. 2025-03-01 HP Weight Reduction for Honda S2000 #37466weightfasterEP Honda S2000 1997cc base loses 75 lbs to 2375; 2157cc base loses 60 lbs to 2450. 2025-03-01 HP Mazda 1999 Miata 1.8L #37488weight -50 lbsfasterEP Mazda MX-5/Miata 99-05 minimum weight drops to 2100 lbs, 2153 lbs with power adder, 2205 lbs with two adders. 2025-03-01 HP MINI Cooper (07-13) Spec Line Correction: Errors and Omissions #37560engineslowerHP Mini Cooper 07-13 engine corrected to DOHC; valve lift limit reduced to 0.390 inches.
	Cal Club 2025 CALCL252025-02-22	2:06.770Lee Fleming · fastest of 4 · top 4 within 4.3s	2:03.082Lee Fleming · fastest of 5 · top 5 within 6.2s	100.4Lee Fleming	1:32.872Jim Devenport · fastest of 3 · top 3 within 8.1s	1:33.972Jim Devenport · fastest of 3 · top 3 within 7.7s	141.7Jim Devenport	-29.110squal -33.898s	76.3%qual 73.3%	2:00.831William Wallis · fastest of 16 · top 5 within 0.9s	2:01.650Nick Leverone · fastest of 16 · top 5 within 0.3s	103.9Evan Jacobs	-1.432squal -5.939s	98.8%qual 95.3%		1:49.596Rob Scholl · only car	116.4Rob Scholl	-13.486s	89.0%
166 earlier rule changes on record, in force before Cal Club 2025 (from 2019)44 cars added · 27 weight · 12 induction · 7 suspension & brakes · 5 engine · 2 aero · 2 tyres & wheels · 67 wording · EP BMW Z3 2.5L requires 52mm flat plate intake restrictor; Z3 2.8L 55mm; 328i/is E36 58mm; 328i/ci E46 58mm; 325i/is E46 56mm; 325i/is E36 56mm; 325is M-Technic 56mm. · Prototype Staudacher and unrestricted engine notes corrected for minimum weight wording. · Prototype class renamed from P1 to P, affecting designation throughout rules with no performance changes. · TA2 rear wing height rule clarified: OEM aerodynamic devices exempt from peak-of-roof requirement. · EP BMW 325i/is E30 (84-91) weight reduced 50–52 lbs across three spec lines to 2150, 2204, 2258. · HP Honda Civic 1.5 88-91 weight reduced to 2175 lbs base, 2229 lbs with one asterisk, 2284 lbs with two asterisks. · HP Mini Cooper 02-06 rear brake rotor increases from 239/9.4 mm/in to 259/10.2. · SMX allows OE instrument cluster relocation for aftermarket dash mounting, with wiring re-routed only; alternate gauges now permitted. · HP Sprite and Midget 1275cc and 1098cc Level 2 compression ratio raised to 12.0:1. · Suzuki Swift GT 89-94 newly classified to HP Pre at 1900 lbs, 1298cc DOHC fuel injected. · SMX Spec MX-5 camera requirement wording changed; non-functioning recorder now grounds for penalty or disqualification. · SMX Spec MX-5 must run latest AIM Data Logger Spec MX-5 ECU Protocol; wording clarification for technical compliance. · SMX Mazda Miata OE versus OEM definitions clarified in GCR Section 9.1.7.1. · SM and SMX shifter bushing rules clarified: alternate bushing at shift lever bottom now allowed. · HP Volkswagen Golf and Jetta 85-92 track correction: front 1537mm (60.5in), rear 1529mm (60.2in). · Nissan 300ZX 84-89 classified to EP at 2550 lbs minimum, 2960cc 6-cyl SOHC, fuel injection, 12.0:1 compression limit, 0.500" valve lift limit. · Mazda RX-7 92-97 newly classified EP Prep Level 2 at 2200–2310 lbs with 13B 6-port rotary engine. · EP Mazda RX-8 (04-11) alternate spec line removed; one primary line remains. · GT2-ST Acura NSX minimum weight raised to 3000 lbs, restrictor increased to 45mm TIR. · HP Honda CRX/Si 84-87 plastic panels can be replaced with replica alternate material if stock appearance maintained. · HP removes four redundant VW spec lines: Rabbit Cabriolet 1780, Scirocco 1588, Scirocco 1780 8-valve, Scirocco 1588. · GT1, GT2, GT3, GTL, GTX rear spoiler maximum surface area limit of 295.0 square inches removed. · GT1/GT2/GT3/GTL/GTX Direct Injection now permitted if OE, using only OE pump, hoses, injectors. · GT2/3 Nissan, Mazda, Mitsubishi 4G93, QR25DE/DD, QE25DE/DD Direct Injection now permitted per 9.1.2.F.7.5.E. · HP Honda Civic 1.5 (88-91) weight reduced to 2175 lbs base, 2229 lbs with power adder, 2284 lbs with two. · GTX adds KTM X-Bow classification with restrictor and weight specifications effective 2024-01-01. · EP BMW Z3 2.5L weight increases to 2500 lbs, 2563 lbs with turbo, 2625 lbs with supercharger. · HP Sprite/Midget Mk I–IV, Mk 1500 compression ratio raised to 12.0:1 at Prep Level 1/2. · HP Triumph Spitfire 1500 valve spec changes from 36.6/5.5/(1.44/0) to 36.6/(1.44). · EP Mazda MX-5 1.8L 1990-97 minimum weight drops to 2150 lbs; 1994-97 variants to 2000, 2050, 2100 lbs respectively. · EP Triumph GT6 dual 1.75" carbs weight drops to 1940 lbs; triple Weber 40 DCOE options consolidated. · EP Honda S2000 fuel injected throttle body inside diameter increases from 62mm to 64mm. · HP Honda CRX/Si 84-87 front header/nose panel may use alternate material if appearance remains stock. · EP Triumph TR8 dry sump allowance moved from carburetor line to notes section. · EP Porsche 944/924S 2.5L and 2.7L weight minimums corrected: 2479cc to 2306/2363 lbs, 2681cc to 2358/2415 lbs. · HP Mazda 2 (11-14) minimum weight increases to 1995 lbs, 2045 lbs with, 2095 lbs with. · GTL spec lines moved to contiguous position with GT2 and GT3; GTA category and spec lines renumbered and moved behind GTL. · HP Honda CRX 1.5 (88-91) weight reduced to 2175 lbs, 2229 lbs, and 2284 lbs across three spec lines. · EP Porsche 944/924S combines 2.5L and 2.7L variants with new weights: 2250–2415 lbs depending on engine and year. · FP Toyota Corolla 2TC loses 43 lbs to 1810; HP Corolla loses 50–52 lbs to 1910–2006. · HP Mazda 626 84-87 weight reduced to 2200 lbs, 2255 lbs, and 2310 lbs across three configurations. · EP Triumph GT6 minimum weight reduced to 1800 lbs. · HP Nissan/Datsun PL510 carburetors allow larger 4mm chokes, replacing 2mm specification. · GTX Ligier LMP3 3.7L NA classified at 2203 lbs with 22 mm restrictor. · GTX Ligier JSP4 newly classified as GTX Misc with restrictor and weight specified. · FP and HP Sprite, Midget, and Spitfire 1500 intake valve size corrected to 36.6/(1.44). · HP Volkswagen Rabbit Cabriolet 1780 removed; Rabbit 1588 and 1715 reclassified with engine sizes and year ranges specified. · Ford Fiesta HP and Chevrolet Sonic FP model year ranges extended from 2016 to 2019. · Fields Cardinal V8 classified in GT1 with Ford V8 engine, 4.9L displacement, 2100 lbs minimum weight. · MGB & MGB-GT HP weight breaks reduced to 2000, 2050, 2100 lbs; new MGB HP Prep 1/2 hybrid added at 2175 lbs. · HP Nissan/Datsun PL510 weight reduced: base 1960 to 1910 lbs, 2009 to 1958 lbs, 2058 to 2006 lbs. · EP, FP, HP cylinder head ports limited to 1 inch maximum depth matching from mating surface. · SM Mazda MX-5 Miata 01-05 weight increases to 2450 lbs, or 2465 with alternate bore. · GT2 TA2 and GTA throttle body part numbers updated to GM 90mm electronic #12570790 or Edelbrock 90mm mechanical #33869 or #3870. · GT taillights may now be original style or a panel graphic with functioning red LED brake lamps; wording change only. · VW New Beetle 2.5L 5-cyl added to EP at 2400–2520 lbs, 2480 cc, fuel injection, comp ratio 12.0:1 max, valve lift 0.500" max. · EP Mazda RX-7 12A/13B gains fuel injection option on dual-y manifold with 42mm choke(s). · EP VW Corrado 92-95 stroke corrected to 90.3 mm, displacement to 2792 cc. · Porsche 992 GT3 Cup Car newly classified in GTX. · EP Subaru BRZ and Toyota 86/Scion FR-S model year ranges updated to 13-20. · GTX Wolf GB08 F1 Ford 52XS V8 added to classification at 1725 lbs minimum weight. · C7 Corvette Grand Sport classified in GTX Misc at 3200 lbs with option to remove displacement on demand valve train. · GTX eligible prototypes expanded: IMSA GTP years changed to 1981-1993, five prototype categories added. · EP Mazda MX-5 Global Cup 16-22 minimum weight set to 2400 lbs; sequential gearbox allowed with +150 lbs penalty. · BMW 128i (08-13) classified in EP at 2700 lbs minimum with stock throttle body, 11.0:1 compression ratio, 0.400 in. valve lift limits. · EP/FP/HP open cars may now use carbon fiber hardtops if they retain OEM appearance in all exterior profiles. · EP Mazda RX-8 13B carburetor rules clarified: dual 2bbl carb, fuel injected throttle body, or stock fuel injection permitted. · EP and FP Production clarifies idle control valve rules: stock devices allowed original, removed with blocked ports, or mechanical replaced with electronic stock type. · HP Volkswagen New Beetle (98-05) classified at 2350 lbs minimum, 1984cc SOHC, fuel injection, 11.0:1 compression limit. · SM Majors must run authorized Penske shock and mount; Regional competitors' requirement eligibility clarified. · GTX McLaren 720s GT3 newly classified at 3000 lbs with 3000 mm restrictor. · HP Triumph Spitfire 1500 minimum weight increases to 1605 lbs, 1645 lbs, or 1685 lbs. · EP BMW Z3 2.5L intake restrictor reduced from 59mm to 58mm flat plate. · Ford Mustang 99-03 classified to EP at 2700/2768/2835 lbs; 94-98 Mustang weight reduced to 2550/2614/2678 lbs. · EP, FP, HP Improved Touring cars may use any DOT-approved tire per section 9.3.45 in Production class. · GTX-FIA GT3 removes all intake restrictor requirements for fifteen car models; McLaren name corrected. · EP, FP, HP classes allow stock/original idle control devices unmodified or completely removed with openings blocked. · HP Fiat X1/9 intake valves corrected to 36.3mm/1.43in; exhaust valves to 33.3mm/1.31in or 31.2mm/1.23in depending on level. · EP Porsche 968 intake valve size increased from 37 to 39.0 mm. · EP, FP, HP front-wheel-drive cars may alter body and suspension to install alternate transmission, transaxle, and axle shaft. · HP Fiat X1/9 1500 loses 50 lbs to 1950; 1300 loses 45–47 lbs; Bertone 1500 loses 50–52 lbs. · Austin-Healey Sprite Mk I, II, III, IV and MG Midget classified in HP Prep with 1510–1586 lbs depending on prep level. · EP BMW Z3 2.5L allows alternate throttle body from 92-95 325i with Turner adapter; head casting 1738400 permitted with specific blocks. · Austin-Healey Sprite Mk I–IV and MG Midget classified in HP with 1655 lbs minimum weight. · EP Porsche 944S2 89-91 requires 56mm flat plate intake restrictor; comp ratio max 12.0:1, valve lift max 0.500". · HP Corolla GTS RWD (84-87) added at 2300 lbs; HP Corolla FX16 FWD (87-88) added at 2260 lbs; old Corolla (84-87) removed. · GT3 Fun Cup Beetle EVO3 classified with 1984 cc sealed SOHC engine, 2060 lbs minimum weight. · HP Toyota MR-2 1.6L (85-89) track corrected to 15.47 inches front and rear. · GTX SRO-GT4 Porsche 718 Club Sport MR GT4 classified, unrestricted, 2900 lbs minimum weight. · GTA part numbers updated: 0-80541-1 to 0-80541-2 in two sections and 6010 to 6014X in TA2 Appendix. · Grullon GT with 2.0L K20 moved from GTX to GT2-ST, minimum weight 2350 lbs, unrestricted. · Honda S2000 (00-03) reclassified as EP Prep with F22c engine option: 1997cc or 2157cc, weight 2450–2636 lbs depending on displacement. · EP Nissan 240-SX S13/S14 loses 200-210 lbs minimum weight; comp ratio rises to 12.0:1, valve lift to .500. · GTX Grullon GT added, unrestricted, 2350 lbs, factory spec required. · EP Lotus/Caterham 7 America carburetor changed from IT fuel injection prep to fuel injection. · Plymouth Arrow 1598cc four-cylinder classified to HP at 1800 lbs minimum weight. · BMW 318i E30 (84-85) reclassified from FP to HP at 2200–2310 lbs with fuel injection and .425" valve lift limit. · Daimler SP 250 classified in EP at 2165 lbs with 2548 cc OHV 8-cylinder engine. · HP Spec Line Porsche 924 (76-84) brakes change from solid to vented disc. · EP, FP, HP clarifies percentage weight penalties sum first, then apply to base weight, rounding to nearest pound. · HP Mazda 626 (84-87) induction changed from dual 32mm sidedraft carbs to carburation or fuel injection. · Volvo 142/142E moves from HP Spec P-1800 Engine to HP Prep with 1989cc OHV four-cylinder, 2450–2573 lbs. · Volkswagen Golf III/Jetta III 93-98 classified to HP at 2325–2441 lbs with 1984cc SOHC engine. · Porsche 924 (76-84) newly classified to HP with 2400-2520 lbs weight, fuel injection, 1984cc engine. · 84-87 Mazda 626 reclassified from FP to HP with 2300–2415 lbs weight, 1998cc SOHC, dual 32mm carbs. · FP Fiat X1/9 brake rotors change to 257 (10.1) x 12 (.407) solid disc. · HP Mini Cooper classification expands to include 12-15 Coupe model in existing spec line. · HP Volkswagen Rabbit GTI 1780 (83-84) permits Mk2 VW front spindles, hubs and bearings. · SM adds procedures for testing obsolete part replacements and BOP updates in sanctioned events with CRB approval. · EP Austin-Healey 3000 Mk. I, II, III now allows TR-6 front calipers and discs as alternate. · FP Volkswagen Golf and Jetta 1.8 lose 50 lbs each, to 1900. HP Jetta GLI engine code removed. · EP, FP, HP Level 1 and Level 2 induction systems: clarified carburetor and fuel injection rules, jets/needles/rods unrestricted in Level 2. · EP Datsun SRL 311U Roadster minimum weight reduced to 1925 lbs from 2000 lbs. · EP Triumph TR8 78-81 weight reduced from 2600 to 2500 lbs. · HP 84-87 Toyota Corolla wheel diameter increases from 13 to 15 inches. · SM aftermarket radiators must mount in original location, maintain core plane, require no body modifications, block openings, keep one OEM fan in stock location; 1990-1997 cars may install upper radiator seal NA75-50-OK7A. · GT1, GT2, GT3, GTL, GTX now permit turbocharging/supercharging if listed on spec line. · GTX Chevrolet Camaro ZL1 LT4 with factory supercharger classified at 3400 lbs minimum weight. · GTX adds KTM X-Bow GT4, turbocharged 2.5L Audi TFSI I5, 2000 lbs minimum weight. · EP BMW Z3 2.5L iron block casting 1738566-C designation removed, wording clarification only. · SM rear brake calipers may use single bracket under upper retaining bolt to prevent pin failure. · TA2 Gurney flap wording clarified: terminology standardized to 'Gurney flap', height limits and thickness specifications remain 0.50 inch / 0.625 inch or 0.375 inch / 0.0625 inch depending on configuration. · STO rear wing wording clarified: 'wicker' changed to 'Gurney flap' in maximum chord and mounting height rules. · GT classes clarify Gurney flap wording, replacing wickerbill/tab terminology with flap; specifications unchanged. · Porsche 911 S 67-68 classified in EP at three weight levels: 1800, 1845, or 1890 lbs. · 1.8 VW GTI Mk1 dual carb request denied; remains stock fuel injection only. · GTX tube frame cars must weigh 2780 pounds; stock car bodies now permitted. · EP BMW 2.8L, 328i E36/E46, and 325i E36 blocks now iron only; 325i E46 aluminum only. · GTX adds Lotus Evora GTS with 3.5L 2GR-FE engine, no restrictor, 2950 lbs minimum weight. · 1990-1994 Mazda Protege classified in FP Pre at 2150–2258 lbs with 1839cc DOHC engine, fuel injection. · HP Mini Cooper model year ranges for convertibles revised: 02-06 now includes 05-08, 07-13 now includes 09-15. · EP Caterham 7 Spec Line removes redundant suspension note, clarifies engine prep limits and comp ratio to 10.0:1. · HP Volkswagen Rabbit and Scirocco 1588 remove 32mm choke requirement, clarify carburetor options and weight penalties. · HP Mini Cooper Convertible (07-13) newly classified; (05-08) convertible spec consolidated into main listing. · HP Datsun 510 Level 2 brakes changed from factory spec to 9.1 disc front, 9.0 drum rear, allowing 240Z/260Z/280Z parts. · HP Datsun 510 gains 40 DCOE carburetor option alongside existing 40 DCN and 36mm DCNVH choices. · HP Ford Fiesta 78-80 minimum weight drops 50 lbs to 1725; both asterisk tiers drop 51 lbs. · GT1, GT2, GT3, GTL, GTX may omit windshield clips if factory glass is bonded per original specifications. · HP Datsun 1200 carburetor choke size increases from 26mm to 30mm. · Factory Five Type 65 Coupe R with Ford 302/351 or 5.0/5.2L NA added to GTX-MISC at 2600 lbs. · HP Mazda2 updates to 11-14, Honda Fit to 15-19, Mini Cooper to 07-13. · HP Porsche 914-4 1.8L now allows 2-stage dry sump if cam-driven and OEM-located. · HP Toyota Corolla 71-74 permitted to use rear axle housing from 84-87 Corolla. · FP and EP Mazda Miata models standardized to 55mm throttle body diameter; brake spec clarified. · HP VW Rabbit Convertible and Scirocco 1.6L lose 50 lbs minimum weight, to 1735. · FP and HP Honda Civic and CRX 1988–91 track specifications corrected to 61.3/61.7 inches. · EP, FP, HP cylinder head rules reorganized for clarity; no performance change. · FP and HP Austin-Healey Sprite Mk I and MG Midget variants may replace rear bodywork aft of cockpit with stock-appearing alternate material components. · EP Mazda MX-5 Global Cup classification year changes from 16-18 to 16-19. · Production suspension rule clarifies spindles, hubs, bushings, bearings, ball joints unrestricted. · Production carb rules clarified: carburetor options, fuel injection throttle body dimensions, and intake manifold restrictions reorganised and refined. · EP, FP, HP carburetors clarified: jets, needles, metering rods, needle valves unrestricted; choke parts removable; permitted optional carburetors listed. · EP Mazda MX-5/Miata eligibility years expanded from 1999-2002 to 1999-2005. · GTX tube frame cars gain fuel injection with 90mm maximum throttle body size. · Ligier JS2 R classified in GTX, no performance parameters specified in filing. · GT1 and GT2/GT3/LITE ride height requirements removed from GCR sections 9.1.2.D.5.a.1 and 9.1.2.F.7.b. · EP, FP, HP clarified: tapered holes in ball joints now allowed for bolt conversion; wheel bearings and hubs unrestricted at any wheel. · EP open cars may now use aftermarket hardtops if they retain OEM appearance; specific model hardtop allowances removed. · GTX replaces all FIA GT4 references with SRO GT4. · HP Toyota Yaris 06-11, 07-12 sedan, 12-18 add 130-136 lbs minimum weight. · HP Ford Fiesta years corrected to 11-16; Mazda hubs D651-33-06 front and D651-26-15XE rear allowed. · SM fuel pump and filter must be Mazda or OEM Equivalent part. · SM 1999-2000 model year cars may use replacement Mazda ECU and injector harnesses, unmodified. · SM electrical rules reorganized and clarified; alternator external regulation now prohibited except via OEM ECU/kill switch. · SM removes tire tread protrusion beyond fender opening requirement from GCR 9.1.7.C.5. · GTX FIA GT3: Audi R8 40mm restrictor 2900 lbs, BMW Z4 70mm 2800 lbs, Ferrari 488 35mm restrictor 3025 lbs classified.showhide 2025-02-21 HP Effective date for Jan 2025 GCR updates #37654inductionslowerEP BMW Z3 2.5L requires 52mm flat plate intake restrictor; Z3 2.8L 55mm; 328i/is E36 58mm; 328i/ci E46 58mm; 325i/is E46 56mm; 325i/is E36 56mm; 325is M-Technic 56mm. 2025-02-01 P Correct text in engine table notes #37606wordingneutralPrototype Staudacher and unrestricted engine notes corrected for minimum weight wording. 2025-02-01 P Update Prototype class designation #37653wordingneutralPrototype class renamed from P1 to P, affecting designation throughout rules with no performance changes. 2025-01-01 GTX Correct language regarding OEM Areo Devices #37137wordingneutralTA2 rear wing height rule clarified: OEM aerodynamic devices exempt from peak-of-roof requirement. 2025-01-01 HP Request to Reduce Weight of BMW 325i/is E30 (84-91) Spec Line #37119weight -50 lbsfasterEP BMW 325i/is E30 (84-91) weight reduced 50–52 lbs across three spec lines to 2150, 2204, 2258. 2025-01-01 HP Request to Update 1988-1991 Civic to Match 1988-1991 CRX #37444weight -70 lbsfasterHP Honda Civic 1.5 88-91 weight reduced to 2175 lbs base, 2229 lbs with one asterisk, 2284 lbs with two asterisks. 2024-12-01 HP MINI Cooper Spec Line Correction - Rear Brake Rotor Diameter #37176suspension & brakesneutralHP Mini Cooper 02-06 rear brake rotor increases from 239/9.4 mm/in to 259/10.2. 2024-12-01 SM E&O SMX Regs 9.1.7.1.D.5.u-.w #37070wordingneutralSMX allows OE instrument cluster relocation for aftermarket dash mounting, with wiring re-routed only; alternate gauges now permitted. 2024-11-01 HP 1275 HP Spridget Level 2 Only #36518enginefasterHP Sprite and Midget 1275cc and 1098cc Level 2 compression ratio raised to 12.0:1. 2024-11-01 HP Request for Classification of 1989-1994 Suzuki Swift GT 16V Twin #36858cars addedneutralSuzuki Swift GT 89-94 newly classified to HP Pre at 1900 lbs, 1298cc DOHC fuel injected. 2024-09-01 SM SMX Camera Rule Correction #36496wordingneutralSMX Spec MX-5 camera requirement wording changed; non-functioning recorder now grounds for penalty or disqualification. 2024-09-01 SM Committee) AIM ECU Protocol #36556wordingneutralSMX Spec MX-5 must run latest AIM Data Logger Spec MX-5 ECU Protocol; wording clarification for technical compliance. 2024-09-01 SM Committee) OE versus OEM Definitons #36608wordingneutralSMX Mazda Miata OE versus OEM definitions clarified in GCR Section 9.1.7.1. 2024-09-01 SM Committee) Shifter Bushing #36611wordingneutralSM and SMX shifter bushing rules clarified: alternate bushing at shift lever bottom now allowed. 2024-08-01 HP Errant entry in HP production line item #36231wordingneutralHP Volkswagen Golf and Jetta 85-92 track correction: front 1537mm (60.5in), rear 1529mm (60.2in). 2024-06-01 HP NIssan 300ZX Z31 to EP #35830cars addedneutralNissan 300ZX 84-89 classified to EP at 2550 lbs minimum, 2960cc 6-cyl SOHC, fuel injection, 12.0:1 compression limit, 0.500" valve lift limit. 2024-06-01 HP RX7 1993 and Up Request In EP Spec Lines, classify #36031cars addedneutralMazda RX-7 92-97 newly classified EP Prep Level 2 at 2200–2310 lbs with 13B 6-port rotary engine. 2024-06-01 HP Clean-up Multiple EP RX-8 Spec Lines In EP #36156wordingneutralEP Mazda RX-8 (04-11) alternate spec line removed; one primary line remains. 2024-05-01 GTX Request for Spec Line 1010 Reconsideration #35009weight +300 lbsslowerGT2-ST Acura NSX minimum weight raised to 3000 lbs, restrictor increased to 45mm TIR. 2024-05-01 HP Replace plastic panels #35875wordingneutralHP Honda CRX/Si 84-87 plastic panels can be replaced with replica alternate material if stock appearance maintained. 2024-03-01 HP GCR Correction - Redundant HP Spec Lines #35623wordingneutralHP removes four redundant VW spec lines: Rabbit Cabriolet 1780, Scirocco 1588, Scirocco 1780 8-valve, Scirocco 1588. 2024-02-01 GTX Rear Blade Spoiler Clarification #35261aerofasterGT1, GT2, GT3, GTL, GTX rear spoiler maximum surface area limit of 295.0 square inches removed. 2024-02-01 GTX GT Direct Injection allowance and rules #35437enginefasterGT1/GT2/GT3/GTL/GTX Direct Injection now permitted if OE, using only OE pump, hoses, injectors. 2024-02-01 GTX GT2/3 remove Direction Injection not allowed in Spec line notes #35439inductionfasterGT2/3 Nissan, Mazda, Mitsubishi 4G93, QR25DE/DD, QE25DE/DD Direct Injection now permitted per 9.1.2.F.7.5.E. 2024-02-01 HP Update 1988-1991 Civic to Match 1988-1991 CRX #35399weightfasterHP Honda Civic 1.5 (88-91) weight reduced to 2175 lbs base, 2229 lbs with power adder, 2284 lbs with two. 2024-01-01 GTX** KTM X Bow GTX #34956cars addedneutralGTX adds KTM X-Bow classification with restrictor and weight specifications effective 2024-01-01. 2024-01-01 HP Request to Review Z3 2.5 Spec Line #35073weight +50 lbsslowerEP BMW Z3 2.5L weight increases to 2500 lbs, 2563 lbs with turbo, 2625 lbs with supercharger. 2024-01-01 HP Parity in HP #35138enginefasterHP Sprite/Midget Mk I–IV, Mk 1500 compression ratio raised to 12.0:1 at Prep Level 1/2. 2024-01-01 HP Spitfire classification #35224wordingunclearHP Triumph Spitfire 1500 valve spec changes from 36.6/5.5/(1.44/0) to 36.6/(1.44). 2024-01-01 HP Miata Alternate Head #35253weight -50 lbsfasterEP Mazda MX-5 1.8L 1990-97 minimum weight drops to 2150 lbs; 1994-97 variants to 2000, 2050, 2100 lbs respectively. 2024-01-01 HP Triumph GT6 Adjustments #35255weightfasterEP Triumph GT6 dual 1.75" carbs weight drops to 1940 lbs; triple Weber 40 DCOE options consolidated. 2024-01-01 HP Honda S2000 throttle body #35272inductionfasterEP Honda S2000 fuel injected throttle body inside diameter increases from 62mm to 64mm. 2024-01-01 HP Front Header/Nose Panel Alternate Material For 84-87 CRX #35301wordingneutralHP Honda CRX/Si 84-87 front header/nose panel may use alternate material if appearance remains stock. 2024-01-01 HP Correction within Triumph TR8 Spec Line #35315wordingneutralEP Triumph TR8 dry sump allowance moved from carburetor line to notes section. 2024-01-01 HP Correction to EP 924S/944 Spec Line #35317wordingneutralEP Porsche 944/924S 2.5L and 2.7L weight minimums corrected: 2479cc to 2306/2363 lbs, 2681cc to 2358/2415 lbs. 2024-01-01 HP Review Classification of HP Mazda 2 #35318weight +75 lbsslowerHP Mazda 2 (11-14) minimum weight increases to 1995 lbs, 2045 lbs with, 2095 lbs with. 2023-12-01 GTX* Errors in GTCS Headings and Use of the Terms Category and ClassChange existing GTL and GTA Rules #34453wordingneutralGTL spec lines moved to contiguous position with GT2 and GT3; GTA category and spec lines renumbered and moved behind GTL. 2023-12-01 HP Request to Adjust Weight of 1988-1991 CRX/Civic #35115weight -70 lbsfasterHP Honda CRX 1.5 (88-91) weight reduced to 2175 lbs, 2229 lbs, and 2284 lbs across three spec lines. 2023-12-01 HP Porsche 944/924S Rule Change Request #35002cars addedneutralEP Porsche 944/924S combines 2.5L and 2.7L variants with new weights: 2250–2415 lbs depending on engine and year. 2023-12-01 HP FP and HP Toyota Corolla #35030weight -43 lbsfasterFP Toyota Corolla 2TC loses 43 lbs to 1810; HP Corolla loses 50–52 lbs to 1910–2006. 2023-12-01 HP Weight Reduction for Mazda 626 #35031weight -100 lbsfasterHP Mazda 626 84-87 weight reduced to 2200 lbs, 2255 lbs, and 2310 lbs across three configurations. 2023-12-01 HP Triumph GT6 Adjustments #35054weight -30 lbsfasterEP Triumph GT6 minimum weight reduced to 1800 lbs. 2023-09-01 HP Larger chokes #34681inductionfasterHP Nissan/Datsun PL510 carburetors allow larger 4mm chokes, replacing 2mm specification. 2023-07-01 GTX Request Ligier LMP3 Classification #34043cars addedneutralGTX Ligier LMP3 3.7L NA classified at 2203 lbs with 22 mm restrictor. 2023-07-01 GTX Ligier JSP4 Request #34173cars addedneutralGTX Ligier JSP4 newly classified as GTX Misc with restrictor and weight specified. 2023-07-01 HP Correct Intake Valve Size on 1500cc Midget/Spitfire #34419wordingneutralFP and HP Sprite, Midget, and Spitfire 1500 intake valve size corrected to 36.6/(1.44). 2023-07-01 HP ITC to FP? #34286cars addedneutralHP Volkswagen Rabbit Cabriolet 1780 removed; Rabbit 1588 and 1715 reclassified with engine sizes and year ranges specified. 2023-06-01 HP Request to Classify Sonic and Fiesta in HP #34264wordingneutralFord Fiesta HP and Chevrolet Sonic FP model year ranges extended from 2016 to 2019. 2023-05-01 GTX Please classify Fields Cardinal V8 #33784cars addedneutralFields Cardinal V8 classified in GT1 with Ford V8 engine, 4.9L displacement, 2100 lbs minimum weight. 2023-01-01 HP MGB HP Weight Break and/or Hybrid 1/2 Prep in HP #33127weightfasterMGB & MGB-GT HP weight breaks reduced to 2000, 2050, 2100 lbs; new MGB HP Prep 1/2 hybrid added at 2175 lbs. 2023-01-01 HP Datsun 510 Help #33568weight -50 lbsfasterHP Nissan/Datsun PL510 weight reduced: base 1960 to 1910 lbs, * 2009 to 1958 lbs, 2058 to 2006 lbs. 2023-01-01 HP Review Limited Prep Port Matching Rules #33600wordingneutralEP, FP, HP cylinder head ports limited to 1 inch maximum depth matching from mating surface. 2023-01-01 SM BOP for NB1 and NB2 #32309weightslowerSM Mazda MX-5 Miata 01-05 weight increases to 2450 lbs, or 2465 with alternate bore. 2022-12-01 GTX GT2 (TA2)/GTA Part Number Update #33315wordingneutralGT2 TA2 and GTA throttle body part numbers updated to GM 90mm electronic #12570790 or Edelbrock 90mm mechanical #33869 or #3870. 2022-09-01 GTX Tail lights on all GT category race cars. #32799wordingneutralGT taillights may now be original style or a panel graphic with functioning red LED brake lamps; wording change only. 2022-09-01 HP Request to classify VW New Beetle 2.5L in EP #32725cars addedneutralVW New Beetle 2.5L 5-cyl added to EP at 2400–2520 lbs, 2480 cc, fuel injection, comp ratio 12.0:1 max, valve lift 0.500" max. 2022-09-01 HP Request Rotary Injection on Dual Y manifold #32775inductionunclearEP Mazda RX-7 12A/13B gains fuel injection option on dual-y manifold with 42mm choke(s). 2022-09-01 HP Request for Corrado Stroke & Displacement Correction #32985wordingneutralEP VW Corrado 92-95 stroke corrected to 90.3 mm, displacement to 2792 cc. 2022-06-01 GTX Classify 992 GT3 Cup #32649cars addedneutralPorsche 992 GT3 Cup Car newly classified in GTX. 2022-06-01 HP Subaru BRZ Model Years #32500wordingneutralEP Subaru BRZ and Toyota 86/Scion FR-S model year ranges updated to 13-20. 2022-05-01 GTX Add Classification to the accepted Model Table #31981cars addedneutralGTX Wolf GB08 F1 Ford 52XS V8 added to classification at 1725 lbs minimum weight. 2022-05-01 GTX Request to classify C7 Corvette Grand Sport IN GTX Misc #32254cars addedneutralC7 Corvette Grand Sport classified in GTX Misc at 3200 lbs with option to remove displacement on demand valve train. 2022-05-01 GTX E&O list of eligible prototypes #32511cars addedneutralGTX eligible prototypes expanded: IMSA GTP years changed to 1981-1993, five prototype categories added. 2022-05-01 HP EP MX-5 Global Cup Car #32218weightslowerEP Mazda MX-5 Global Cup 16-22 minimum weight set to 2400 lbs; sequential gearbox allowed with +150 lbs penalty. 2022-05-01 HP Please Class BMW 128i in EP #32370cars addedneutralBMW 128i (08-13) classified in EP at 2700 lbs minimum with stock throttle body, 11.0:1 compression ratio, 0.400 in. valve lift limits. 2022-05-01 HP Inconsistency in Body Work Descriptions #32396aerofasterEP/FP/HP open cars may now use carbon fiber hardtops if they retain OEM appearance in all exterior profiles. 2022-04-01 HP Mazda RX8 with 13b Rotary #32170wordingneutralEP Mazda RX-8 13B carburetor rules clarified: dual 2bbl carb, fuel injected throttle body, or stock fuel injection permitted. 2022-04-01 HP Request Idle control valve clarification #32178wordingneutralEP and FP Production clarifies idle control valve rules: stock devices allowed original, removed with blocked ports, or mechanical replaced with electronic stock type. 2022-04-01 HP Classify VW New Beetle in HP. #32241cars addedneutralHP Volkswagen New Beetle (98-05) classified at 2350 lbs minimum, 1984cc SOHC, fuel injection, 11.0:1 compression limit. 2022-04-01 SM Update GCR Section 9.1.7.3.A.1. #32217wordingneutralSM Majors must run authorized Penske shock and mount; Regional competitors' requirement eligibility clarified. 2022-03-01 GTX McLaren 720s GT3 #31955cars addedneutralGTX McLaren 720s GT3 newly classified at 3000 lbs with 3000 mm restrictor. 2022-03-01 HP Weight Change for Competition Adjustment #31182weight +45 lbsslowerHP Triumph Spitfire 1500 minimum weight increases to 1605 lbs, 1645 lbs, or 1685 lbs. 2022-03-01 HP EP Adjustments #31858inductionslowerEP BMW Z3 2.5L intake restrictor reduced from 59mm to 58mm flat plate. 2022-03-01 HP 1999 3.8L Ford Mustang to EP? #31635weightfasterFord Mustang 99-03 classified to EP at 2700/2768/2835 lbs; 94-98 Mustang weight reduced to 2550/2614/2678 lbs. 2022-03-01 HP Improved Touring Tires #32064tyres & wheelsneutralEP, FP, HP Improved Touring cars may use any DOT-approved tire per section 9.3.45 in Production class. 2022-02-01 GTX Remove restrictions from GTX-FIA GT3 #32039inductionfasterGTX-FIA GT3 removes all intake restrictor requirements for fifteen car models; McLaren name corrected. 2022-02-01 HP Throttle Body and Idle Air #31800wordingneutralEP, FP, HP classes allow stock/original idle control devices unmodified or completely removed with openings blocked. 2022-02-01 HP Incorrect Valve Size Changes in Jan 2022 GCR for FIAT X1/9 #31990wordingunclearHP Fiat X1/9 intake valves corrected to 36.3mm/1.43in; exhaust valves to 33.3mm/1.31in or 31.2mm/1.23in depending on level. 2022-01-01 HP Porsche 968 Engine Questions #31478enginefasterEP Porsche 968 intake valve size increased from 37 to 39.0 mm. 2022-01-01 HP PCS E. 2. n. 4. Add Axle Shaft to Allow FWD the Same Freedom #31592wordingneutralEP, FP, HP front-wheel-drive cars may alter body and suspension to install alternate transmission, transaxle, and axle shaft. 2022-01-01 HP Weight Adjustment To Fiat X1/9 Spec Lines, H-Production #31653weight -50 lbsfasterHP Fiat X1/9 1500 loses 50 lbs to 1950; 1300 loses 45–47 lbs; Bertone 1500 loses 50–52 lbs. 2022-01-01 HP 1500 Midget #31665cars addedneutralAustin-Healey Sprite Mk I, II, III, IV and MG Midget classified in HP Prep with 1510–1586 lbs depending on prep level. 2022-01-01 HP BMW Z3 2.5L Spec Line #31724wordingneutralEP BMW Z3 2.5L allows alternate throttle body from 92-95 325i with Turner adapter; head casting 1738400 permitted with specific blocks. 2022-01-01 HP Request weight requirement for 1500 MG Midget #31802cars addedneutralAustin-Healey Sprite Mk I–IV and MG Midget classified in HP with 1655 lbs minimum weight. 2021-12-01 HP 944S2 Restrictor #31396inductionslowerEP Porsche 944S2 89-91 requires 56mm flat plate intake restrictor; comp ratio max 12.0:1, valve lift max 0.500". 2021-12-01 HP Classing Clarification for 1986 Toyota Corolla FX16 #31527cars addedneutralHP Corolla GTS RWD (84-87) added at 2300 lbs; HP Corolla FX16 FWD (87-88) added at 2260 lbs; old Corolla (84-87) removed. 2021-10-01 GTX Request car classification #31032cars addedneutralGT3 Fun Cup Beetle EVO3 classified with 1984 cc sealed SOHC engine, 2060 lbs minimum weight. 2021-10-01 HP E&O; MR2 Track #31120wordingneutralHP Toyota MR-2 1.6L (85-89) track corrected to 15.47 inches front and rear. 2021-09-01 GTX Request to classify 2020 Porsche 718 GT4 Clubsport MR #30956cars addedneutralGTX SRO-GT4 Porsche 718 Club Sport MR GT4 classified, unrestricted, 2900 lbs minimum weight. 2021-08-01 GTX Request to Update GTA Obsolete Part Numbers #30615wordingneutralGTA part numbers updated: 0-80541-1 to 0-80541-2 in two sections and 6010 to 6014X in TA2 Appendix. 2021-08-01 GTX GTX class correction to GT2/ST #30973cars addedneutralGrullon GT with 2.0L K20 moved from GTX to GT2-ST, minimum weight 2350 lbs, unrestricted. 2021-08-01 HP Request to Allow F22c Engine for 2000-2003 Honda S2000 #30548cars addedunclearHonda S2000 (00-03) reclassified as EP Prep with F22c engine option: 1997cc or 2157cc, weight 2450–2636 lbs depending on displacement. 2021-08-01 HP Request a review of the S14 240SX in EP. #30873weight -200 lbsfasterEP Nissan 240-SX S13/S14 loses 200-210 lbs minimum weight; comp ratio rises to 12.0:1, valve lift to .500. 2021-07-01 GTX Request classification of Grullon #30481cars addedneutralGTX Grullon GT added, unrestricted, 2350 lbs, factory spec required. 2021-07-01 HP Lotus/Caterham 7 America Request #30392wordingunclearEP Lotus/Caterham 7 America carburetor changed from IT fuel injection prep to fuel injection. 2021-07-01 HP Request to classify ITC Plymouth Arrow #30588cars addedneutralPlymouth Arrow 1598cc four-cylinder classified to HP at 1800 lbs minimum weight. 2021-07-01 HP Reclassification of the 1984/85 BMW 318i from FP to HP #30661cars addedneutralBMW 318i E30 (84-85) reclassified from FP to HP at 2200–2310 lbs with fuel injection and .425" valve lift limit. 2021-07-01 HP Reclassify Daimler SP 250 #30721cars addedneutralDaimler SP 250 classified in EP at 2165 lbs with 2548 cc OHV 8-cylinder engine. 2021-06-01 HP 924 Brakes- and Thank You. #30614suspension & brakesfasterHP Spec Line Porsche 924 (76-84) brakes change from solid to vented disc. 2021-06-01 HP Clarify Application of Percentage Based Weight Penalties #30669weightslowerEP, FP, HP clarifies percentage weight penalties sum first, then apply to base weight, rounding to nearest pound. 2021-06-01 HP Correct Induction Error on new HP Mazda 626 Spec Line #30702inductionunclearHP Mazda 626 (84-87) induction changed from dual 32mm sidedraft carbs to carburation or fuel injection. 2021-05-01 HP Volvo 142 spec line complete. #29479cars addedneutralVolvo 142/142E moves from HP Spec P-1800 Engine to HP Prep with 1989cc OHV four-cylinder, 2450–2573 lbs. 2021-05-01 HP Request to Classify 93-98 Volkswagen Golf to HP #29790cars addedneutralVolkswagen Golf III/Jetta III 93-98 classified to HP at 2325–2441 lbs with 1984cc SOHC engine. 2021-05-01 HP Appeal of Request to Move Porsche 924 to HP #30132cars addedneutralPorsche 924 (76-84) newly classified to HP with 2400-2520 lbs weight, fuel injection, 1984cc engine. 2021-05-01 HP Change Classification of 84-87 Mazda 626 from FP to HP #30350cars addedneutral84-87 Mazda 626 reclassified from FP to HP with 2300–2415 lbs weight, 1998cc SOHC, dual 32mm carbs. 2021-05-01 HP Fiat X1/9 brake rotors #30423suspension & brakesneutralFP Fiat X1/9 brake rotors change to 257 (10.1) x 12 (.407) solid disc. 2021-04-01 HP Request to Classify 2012-2015 MINI Cooper Coupe in HP #30167cars addedneutralHP Mini Cooper classification expands to include 12-15 Coupe model in existing spec line. 2021-04-01 HP Request clarification on VW 1.8 Rabbit GTI Spec Line #30368wordingneutralHP Volkswagen Rabbit GTI 1780 (83-84) permits Mk2 VW front spindles, hubs and bearings. 2021-04-01 SM Updates - Obsolete Parts & BOP Parts #30438wordingneutralSM adds procedures for testing obsolete part replacements and BOP updates in sanctioned events with CRB approval. 2021-01-01 HP Alternate Front Brake Rotors and Calipers for EP AH 3000 #29893suspension & brakesneutralEP Austin-Healey 3000 Mk. I, II, III now allows TR-6 front calipers and discs as alternate. 2020-12-01 HP Mk2 VW Consistency and Cleanup of FP and HP Spec Lines #29195weight -50 lbsfasterFP Volkswagen Golf and Jetta 1.8 lose 50 lbs each, to 1900. HP Jetta GLI engine code removed. 2020-12-01 HP Correct Wording for Level 1 and Level 2 Induction Systems #29406wordingneutralEP, FP, HP Level 1 and Level 2 induction systems: clarified carburetor and fuel injection rules, jets/needles/rods unrestricted in Level 2. 2020-12-01 HP Weight Reduction for Datsun Roadster #29409weight -75 lbsfasterEP Datsun SRL 311U Roadster minimum weight reduced to 1925 lbs from 2000 lbs. 2020-12-01 HP EP TR8 Adjustment #29512weight -100 lbsfasterEP Triumph TR8 78-81 weight reduced from 2600 to 2500 lbs. 2020-10-01 HP 84-87 Toyota Corolla HP Wheel Diameter Allowance Proposal E&O #29458tyres & wheelsfasterHP 84-87 Toyota Corolla wheel diameter increases from 13 to 15 inches. 2020-10-01 SM Radiator E&O Clarifications #29294wordingneutralSM aftermarket radiators must mount in original location, maintain core plane, require no body modifications, block openings, keep one OEM fan in stock location; 1990-1997 cars may install upper radiator seal NA75-50-OK7A. 2020-09-01 GTX GT Category Wording #29193wordingunclearGT1, GT2, GT3, GTL, GTX now permit turbocharging/supercharging if listed on spec line. 2020-08-01 GTX Request Car classification #28935cars addedneutralGTX Chevrolet Camaro ZL1 LT4 with factory supercharger classified at 3400 lbs minimum weight. 2020-08-01 GTX X-Bow GT4 #29088cars addedneutralGTX adds KTM X-Bow GT4, turbocharged 2.5L Audi TFSI I5, 2000 lbs minimum weight. 2020-08-01 HP EP BMW Z3 Rule Clarification #28998wordingneutralEP BMW Z3 2.5L iron block casting 1738566-C designation removed, wording clarification only. 2020-08-01 SM Modifications to prevent failures of Rear Brake Caliper Pin #28953suspension & brakesneutralSM rear brake calipers may use single bracket under upper retaining bolt to prevent pin failure. 2020-07-01 GTX TA2 Gurney flap wicker clarification #28874wordingneutralTA2 Gurney flap wording clarified: terminology standardized to 'Gurney flap', height limits and thickness specifications remain 0.50 inch / 0.625 inch or 0.375 inch / 0.0625 inch depending on configuration. 2020-07-01 GTX STO Gurney flap wicker clarification #28883wordingneutralSTO rear wing wording clarified: 'wicker' changed to 'Gurney flap' in maximum chord and mounting height rules. 2020-07-01 GTX GT Gurney flap wicker clarification #28909wordingneutralGT classes clarify Gurney flap wording, replacing wickerbill/tab terminology with flap; specifications unchanged. 2020-07-01 HP Request to Classify Porsche 911 2.0L #28456cars addedneutralPorsche 911 S 67-68 classified in EP at three weight levels: 1800, 1845, or 1890 lbs. 2020-07-01 HP Request Dual Carbs for 1.8 VW GTI Mk1 #28922wordingneutral1.8 VW GTI Mk1 dual carb request denied; remains stock fuel injection only. 2020-06-01 GTX Request to Re-classify SP Stock car to GTX #28333cars addedneutralGTX tube frame cars must weigh 2780 pounds; stock car bodies now permitted. 2020-06-01 HP BMW Cylinder Head Casting and Part Numbers #28708engineslowerEP BMW 2.8L, 328i E36/E46, and 325i E36 blocks now iron only; 325i E46 aluminum only. 2020-05-01 GTX Request to Classify Lotus Evora GTS #27057cars addedneutralGTX adds Lotus Evora GTS with 3.5L 2GR-FE engine, no restrictor, 2950 lbs minimum weight. 2020-05-01 HP Request to Classify 1990-1994 Mazda Protege #28381cars addedneutral1990-1994 Mazda Protege classified in FP Pre at 2150–2258 lbs with 1839cc DOHC engine, fuel injection. 2020-05-01 HP Error in Mini Cooper Spec Line #28713wordingneutralHP Mini Cooper model year ranges for convertibles revised: 02-06 now includes 05-08, 07-13 now includes 09-15. 2020-04-01 HP Caterham 7 Spec Line #28498wordingneutralEP Caterham 7 Spec Line removes redundant suspension note, clarifies engine prep limits and comp ratio to 10.0:1. 2020-03-01 HP Letter #27917 #28085wordingneutralHP Volkswagen Rabbit and Scirocco 1588 remove 32mm choke requirement, clarify carburetor options and weight penalties. 2020-03-01 HP Request to Classify 2007 - 2013 Mini Cooper Convertible #28111cars addedneutralHP Mini Cooper Convertible (07-13) newly classified; (05-08) convertible spec consolidated into main listing. 2020-03-01 HP Allow HP Datsun 510 Under Level 2 to Utilize Datsun Z Brakes #28121suspension & brakesneutralHP Datsun 510 Level 2 brakes changed from factory spec to 9.1 disc front, 9.0 drum rear, allowing 240Z/260Z/280Z parts. 2020-03-01 HP Request to allow 40 DCOE carb for the Datsun 510 #28195inductionfasterHP Datsun 510 gains 40 DCOE carburetor option alongside existing 40 DCN and 36mm DCNVH choices. 2020-03-01 HP Request Ford Fiesta Weight Adjustment #28337weightfasterHP Ford Fiesta 78-80 minimum weight drops 50 lbs to 1725; both asterisk tiers drop 51 lbs. 2020-02-01 GTX Windshield Clips #27323wordingneutralGT1, GT2, GT3, GTL, GTX may omit windshield clips if factory glass is bonded per original specifications. 2020-02-01 HP Request for Help for Datsun 1200 #27934inductionfasterHP Datsun 1200 carburetor choke size increases from 26mm to 30mm. 2020-01-01 GTX Request Factory Five Daytona coupe classification #26308cars addedneutralFactory Five Type 65 Coupe R with Ford 302/351 or 5.0/5.2L NA added to GTX-MISC at 2600 lbs. 2020-01-01 HP Update years for the Mazda2, Honda Fit, & Mini #27782wordingneutralHP Mazda2 updates to 11-14, Honda Fit to 15-19, Mini Cooper to 07-13. 2020-01-01 HP Allow Dry Sump, Limited Prep Porsche 914 #27814wordingneutralHP Porsche 914-4 1.8L now allows 2-stage dry sump if cam-driven and OEM-located. 2020-01-01 HP Please Allow Alternate Rear Axle Housing for RWD Toyota Corolla #27854wordingneutralHP Toyota Corolla 71-74 permitted to use rear axle housing from 84-87 Corolla. 2020-01-01 HP Request to List Mazda Miata Throttle Body Size #27907wordingneutralFP and EP Mazda Miata models standardized to 55mm throttle body diameter; brake spec clarified. 2020-01-01 HP HP VW Rabbit Convertible 1.6L #1922 and 32mm chokes #27917weightfasterHP VW Rabbit Convertible and Scirocco 1.6L lose 50 lbs minimum weight, to 1735. 2019-12-01 HP Request to Correct Track of 1988-91 Honda Civic #27487wordingneutralFP and HP Honda Civic and CRX 1988–91 track specifications corrected to 61.3/61.7 inches. 2019-12-01 HP Re-organize Prep2 Cylinder Head Rules for Clarity & Consistency #27661wordingneutralEP, FP, HP cylinder head rules reorganized for clarity; no performance change. 2019-08-31 HP Request bodywork for Austin Healey Bugeye Sprite MK1 #27106wordingneutralFP and HP Austin-Healey Sprite Mk I and MG Midget variants may replace rear bodywork aft of cockpit with stock-appearing alternate material components. 2019-08-31 HP Request to classify the GMX5 2019 #27263wordingneutralEP Mazda MX-5 Global Cup classification year changes from 16-18 to 16-19. 2019-08-31 HP level one susp. component rule #27270wordingneutralProduction suspension rule clarifies spindles, hubs, bushings, bearings, ball joints unrestricted. 2019-08-31 HP Clarification of Carb Rules - Prep 1 #27300wordingneutralProduction carb rules clarified: carburetor options, fuel injection throttle body dimensions, and intake manifold restrictions reorganised and refined. 2019-08-31 HP Clarification of Carb Rules - Prep 2 #27301wordingneutralEP, FP, HP carburetors clarified: jets, needles, metering rods, needle valves unrestricted; choke parts removable; permitted optional carburetors listed. 2019-08-01 HP Request Miata Eligibility - 2003 #27121cars addedneutralEP Mazda MX-5/Miata eligibility years expanded from 1999-2002 to 1999-2005. 2019-05-01 GTX Request GTX Fuel injection for previous GT-1 tube frame cars #26141inductionfasterGTX tube frame cars gain fuel injection with 90mm maximum throttle body size. 2019-05-01 GTX Request to Classify Ligier JS2 R #26535cars addedneutralLigier JS2 R classified in GTX, no performance parameters specified in filing. 2019-04-01 GTX Request Ride Height Clarification #26600wordingneutralGT1 and GT2/GT3/LITE ride height requirements removed from GCR sections 9.1.2.D.5.a.1 and 9.1.2.F.7.b. 2019-04-01 HP Rollcenter Correction Clarification #25873suspension & brakesfasterEP, FP, HP clarified: tapered holes in ball joints now allowed for bolt conversion; wheel bearings and hubs unrestricted at any wheel. 2019-04-01 HP Hardtops #26476wordingneutralEP open cars may now use aftermarket hardtops if they retain OEM appearance; specific model hardtop allowances removed. 2019-03-01 GTX Replace FIA references with SRO #26427wordingneutralGTX replaces all FIA GT4 references with SRO GT4. 2019-03-01 HP Do Something About the Toyota Yaris In H Production #25834weight +130 lbsslowerHP Toyota Yaris 06-11, 07-12 sedan, 12-18 add 130-136 lbs minimum weight. 2019-03-01 HP Request to Allow 2011+ Fiesta to Change Bolt Pattern on Wheels #25929wordingneutralHP Ford Fiesta years corrected to 11-16; Mazda hubs D651-33-06 front and D651-26-15XE rear allowed. 2019-03-01 SM Request to allow aftermarket fuel filters. #26370wordingneutralSM fuel pump and filter must be Mazda or OEM Equivalent part. 2019-02-01 SM Request 99-00 replacement Wire harnesses #25602wordingneutralSM 1999-2000 model year cars may use replacement Mazda ECU and injector harnesses, unmodified. 2019-02-01 SM Organize and Clarify 9.1.7.C.1.o. #25913wordingneutralSM electrical rules reorganized and clarified; alternator external regulation now prohibited except via OEM ECU/kill switch. 2019-02-01 SM Strike Tire Tread Language #26123wordingneutralSM removes tire tread protrusion beyond fender opening requirement from GCR 9.1.7.C.5. 2019-01-01 GTX** GTX Homologation table update #26034cars addedneutralGTX FIA GT3: Audi R8 40mm restrictor 2900 lbs, BMW Z4 70mm 2800 lbs, Ferrari 488 35mm restrictor 3025 lbs classified.

Best is the class's fastest lap in that event's qualifying or race sessions, with the driver who set it, how many cars set a time that session and how close the top five were; a best from fewer than three cars is greyed. With two or more classes, "vs" is the gap of each class's best to the first class's at the same event. "% of HP" is the class's best as a share of HP's best at the same event (100% is level, less is quicker): weather and track condition move every class together, so this compares across years where the raw times do not. It still breaks when HP's own field changes or one session was wet and another dry. Newest event first. The coloured figure under each value is the change from the previous event that has one (green is quicker, red slower). Whole laps only, so events with different sector layouts still compare. Weather and track condition are not accounted for.