there is a small error in the classing, a 1998cc evo or wrx could be considered under 3litre... many rally rules use a 1.7 for petrol and 1.5 for diesel forced induction, in addition a .8 multiplier for Pushrod engines. (so the big v6 GM/ford cars can be under 3 litre) also a 1.5 is used for a rotary so a turbo rotary motor would be. 1.3x1.5x1.7 = 3.3 litre. much more reasonable set of groupings.