Someone please back me up on this (Adrian?), but I'm pretty sure this is accurate:
- There isn't a multiplier for AWD or 4WD in production any more - in Production, the only multipliers are1.7 for a turbo/supercharger and 1.5 for a rotary engine.
- for a displacement of 1.8 l, the adjusted displacement would be 3.06 l for turbo, 1.8 l for normally aspirated.
- the magic number that you'd have to worry about is 2.0 l, which is the upper limit of P3 and the lower limit of P4, so...
- A 1.8 l displacement would put you into P3 if it's normally aspirated, P4 if it's turbocharged.
The displacement limits & adjustments are covered under B.II.D.10, and the Production classes are dealt with under B.II.G.3.
Please note that what I said about multipliers is only true for production - there are still others for Group 2.
Jeff Hagan