here it is;

P1
Audi R10 TDi
Audi R8 FSi (for privateers)
Peugeot 908 HDi
Bentley EXP Speed 8
Toyota GT-One
BMW V12 LMR
Panoz LMP-1 Roadster S
Cadillac Northstar LMP
Mercedes CLK-LM
Dome
Courage LC70
Porsche RS Spyder (with more weight and power to match the P1 rules !)

P2, no cars at all !

GT1:
Corvette C6-R
Maserati MC12
Chrysler Viper GTS-R (the old one)
Saleen S7-R
Ferrari 550 Maranello
Ferrari 575 GTC
Aston Martin DBR9
Aston Martin Vanquish
Porche 997 Turbo
Jajuar XKR
Nissan 350Z "GT500"
Honda NSX "GT500"

GT2:
Ferrari F430 GTC
Porsche 997 GT3 RSR
Cadillac CTS-V "Speed World Challenge"
Dodge Viper Coupe
Nissan 350Z
BMW M3 GTR
Pontiac "Grand-Am"
TVR
Marcos Mantis
Morgan Aero 8 LM
Subaru Impreza WRX STi....
Mitsubishi Lancer Evo 9
Mercedes CL55 AMG
Audi RS4

but shmae its all about dreaming