Look at the ancestors of the Mini. Which is your favorite? I love Mini's for their smallness and character. This site shows plenty of mini cars, starting with my favorite:
http://www.microcarmuseum.com/tour/alicante.html

 

I believe that Isogonis designed the original Mini as a reaction to these bubble cars, which he despised. I like the Isettas and Messerschmits (sp?) the best. I've had a few subaru 360s and they are an absolute blast to drive - 0 to 45 is about 60 seconds; 0 to 60 time = never.