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  Home > Specials > Regulations > Car classifications
The diversity of the cars that have been and are being rallied is staggering. Since small citycar is no match for a big engined sports car, how should different types of cars relate to each others and should there be equality rules? In early days there were rules that penalized cars with bigger engines but currently the principle is to divide cars in groups and classes to compete against similar cars rather than against all the other cars.

New regulations - 2011
From 2011, classes are no longer tied to specific groups but rather are a mix of similarly performing cars from different groups. This results a quite an impressive list of classes, at least for time being until older groups are phased out.

 Classes   Groups 
 WRC (A0)   WRC (2011): 1.6T engine with WRC kit 
 A1   S2000-Rally: 1.6T engine 
 A2   S2000-Rally: 2.0 atmospheric
 Group R4 cars 
 A3   Group N car over 2000cc (former N4) 
 A4   RGT cars 
 A5   Group A car 1601-2000 cc
 Super 1600 cars
 R2C, R3C, R3T and R3D cars 
 A6   Group A car 1401-1600cc
 R2B cars
 kit car 1401-1600cc 
 A7   Group A car up to 1400cc
 kit car up to 1400cc 
 A8   Group N car 1601-2000cc 
 A9   Group N car 1401-1600cc
 R1B cars 
 A10   Group N car up to 1400cc
 R1A cars 

Groups and classes
Since 1981, there have been two groups, N and A. These were introduced, alongside groups like B and S, to replace the original numeric groups 1 to 5 which were used in 1973-1981. To put it short, Group N is a standard car with very few modifications allowed whereas Group A is fully prepared racing car. Classes within group are based on cubic capacity of the car as follows.

Group N  production cars
Group A  modified road-going cars

 Cubic capacity   Group N   Group A 
 1400cc or less   N1   A5 
 1401-1600cc   N2   A6 (incl. S1600) 
 1601-2000cc   N3   A7 (incl. F2) 
 over 2000cc   N4   A8 (incl. WRC) 

Note: S1600, F2 and WRC (World Rally Car) are not groups or classes themselves. Those are only technical rules pertaining to how a manufacturer can modify a standard car in order to homologate it.
Minimum production quantity is 2,500 identical models in 12 months for a car to qualify for homologation.

Cars with forced induction (ie. turbo) have their cubic capacity multiplied by 1.7 when calculating class. This is why all A8 cars are in class eight even though their nominal cylinder capacity is slightly below 2000cc.

In the interests of equality, all cars with forced induction must be fitted with engine fresh air intake restrictor. The diameter of the restrictor is 32mm in Group N and 34mm in Group A.

Old groups
Numerical groups were used until December 1981 when they were replaced by current alphabetical groups. During transition period, cars remained much the same and were rallied with temporary classifications.

Group 1: Series Production Touring Cars
Equivalent to current Group N, these were regular four-seated, unmodified production cars with minimum of 5000 units built annually.

Group 2: Special Touring Cars
Equivalent to current Group A, these were regular production cars modified for rally use. Minimum annual production was 1000 units. When Group 1 cars were modified, they became Group 2 cars.

Group 3: Series Production Grand Touring Cars
Grand touring (GT) or sports cars with minimum of 1000 units built annually. Preparation according to obligatory manufacturer homologation, minimal modifications only.

Group 4: Special Grand Touring Cars
Sport cars modified for rally use, minimum of 500 units built annually. When Group 3 cars were modified, they became Group 4 cars.

Group 5 and 6: Prototype cars
Extrapolated freely from unmarketed prototypes, no minimum production requirements.

These classifications are used in WRC. National sporting authorities may use different naming conventions for national series though technical regulations are the same.