There are some great ones in here: http://oldconceptcars.com/
The Lamborghini LM002 had some friends: Cheetah (http://oldconceptcars.com/1930-2004/lamborghini-cheetah-prototype-1977/), LM001 (http://oldconceptcars.com/1930-2004/lamborghini-lm001-1981/), and LM004 (http://oldconceptcars.com/1930-2004/lamborghini-lm004-1984/)!
One of my own favorites is the DAF Siluro (http://oldconceptcars.com/1930-2004/daf-siluro-michelotti-1968/). It's just a completely standard DAF 55 under the hood, a shopping cart with a stepless automatic transmission (but quite the fun rally car nonetheless because of its light weight), but from the right angle it looks like a very stylish sleek fast pipsqueak.