Quote - 3d warehouse has a ton of Prius models... of course you'll need to convert them to obj to be useful, but other than that' they are free. Easiest way to convert is to download the demo of the pro version of Sketchup which will allow you to convert to OBJ.

http://sketchup.google.com/3dwarehouse/search?q=prius&styp=m&btnG=Search

or just use the Free edition with Whaaats UVMapper Ruby (exports to OBJ) or the Free Editions Collada Export and convert from there (Wings will do Collada / OBJ for instance)