Proper Drag Racing Cars
Ones with oh lets say...7000HP!
Top Fuel, Funny Car
or even Pro Modified Versions of the cars already on the game.

http://www.santapod.co.uk/g_gallery_detail.php?PhotoID=9
http://www.santapod.co.uk/g_gallery_detail.php?PhotoID=10

check the pics to see what i mean!!

or the Rolex Grand-Am championship

http://www.toyota.com/motorsports/images/grandam/main.jpg

and maybe even....

TRUE Supercars

that means= Mclaren F1, Ferrari Enzo, TVR Speed 12 Etc

http://www.fast-autos.net/mclaren/f1lm13.jpg