I don't even know if there's room for it under our hood, but I have a crush on the 3L BMW inline six clean diesel engine they put in the rally fighter. Man that thing is sexy. Not a ton of hp but a crapload of torque.

http://jalopnik.com/5398878/rally-fi...hotos/gallery/

http://www.youtube.com/watch?v=7HMk4yu1I4U