The register
Every entry, by section
Motor racing regulations and the cars built to them.
1.1Production minimumsGroup B, Appendix J: two hundred examples in twelve consecutive months, with no restriction on drive layout or induction — and a long argument about what counted as an example..1.2The ficheThe homologation form fixed what the car was; anything not on it was illegal, which made the document itself a design constraint..1.3Evolution modelsTwenty evolution cars were permitted on top of the two hundred, which is how a class built for production cars ended up with purpose-built prototypes..1.4Group A and Group NGroup A took the top class for 1987 and required five thousand cars, which changed who could enter and what they could enter with..
02
Group B
2.1Group BThe class allowed four-wheel drive, turbocharging and a run of only two hundred cars, and inside four years produced the Quattro, the Delta S4 and the 205 T16.2.2Audi QuattroIngolstadt built a four-wheel-drive rally car once the regulations stopped forbidding one; Ferdinand Piëch signed it off, and Michèle Mouton and Walter Röhrl drove it..2.3Lancia Delta S4Abarth in Turin read a rulebook that limited neither supercharging nor turbocharging and fitted both; Sergio Limone led the design and it won the RAC Rally on its debut..2.4Peugeot 205 T16Mid-engined and four-wheel drive, sharing a name with a front-wheel-drive hatchback and very little else; Jean Todt's team took the 1985 and 1986 titles..2.5Group S, cancelledPrototypes were built for a category that was dropped before it ran a single event..
3.1Ground effectColin Chapman's Lotus 78 and 79 used the underside of the car as a wing, and the rules had not thought to say anything about it..3.2Sliding skirtsThe seal between the floor and the road was what made the downforce, and banning it for 1981 removed most of the effect at a stroke..3.3The fan carsGordon Murray's Brabham BT46B, cooled by a fan that also extracted air from beneath the car, won at Anderstorp in 1978 and was withdrawn afterwards..3.4Flat floorsA mandatory flat floor from 1983 wrote the shape of the underbody into the rules and moved the argument to the diffuser behind it..
4.11.5-litre turbosFormula One had carried an equivalence since 1966 — three litres atmospheric, 1.5 with a compressor — and for eleven years nobody built the smaller engine.4.2Boost limitsA mandatory pop-off valve held boost at 4 bar for 1987 and 2.5 bar for 1988, which did the legislating that a power limit never could..4.3Fuel allowancesRefuelling was prohibited for 1984 and the race allowance fixed at 220 litres, then 195, then 150, while atmospheric cars carried as much as they liked..4.4Qualifying enginesBy the middle of the decade qualifying outputs were quoted as estimates rather than measurements, because the figures ran past the equipment used to read them..
5.1Gauges and templatesA rule is only as good as the tool that checks it, and a surprising number of regulations are written around the shape of a template..5.2Weight and ballastMinimum weight is checked after the event with the car as it finished, which is why ballast placement is a design decision rather than an afterthought..5.3ProtestsA protest is a formal document with a deadline and a fee, and it is how most regulations actually get interpreted..5.4ExclusionsCars are excluded for measurements, not for intentions, which is the whole reason scrutineering exists..
6.1Pushrod boost at IndianapolisA concession written to keep older pushrod engines competitive was read literally in 1994 and answered with a purpose-built engine that used all of it..6.2Six wheelsNothing in the wording said four, so somebody built six — and the rules were rewritten afterwards to say four..6.3Movable devicesAerodynamic devices must be fixed and immobile, a sentence that has been argued over continuously since it was written..
7.1Corsica, 1986The Tour de Corse of 1986 is the round after which the class was abolished.7.2Fuel cellsThe rubber bladder tank with a foam core is a specification written into the rulebook, with a service life and a stamped date on it..7.3Survival cellsThe tub is tested to a written load case before the car is allowed to race, and the test is the regulation..