Wow. It's very hard to come up with a short list. Totally impossible to come up with just 1.
1935 Auburn boat-tail speedster
http://www.californiaclassix.com/arc...burn_c167.html
190x Rolls Royce Silver Ghost
http://www.rrab.com/rsg_gb.htm
Lotec Sirius concept
http://www.supercars.net/cars/2001@$Lotec@$Sirius%20Conceptg.html (drool, even if it's 0-60 time is too slow for its power)
I'll second the Jag E-type too.