I saw an Elise, nice lookin' cars. Honestly though, for $40k I'd buy something else.
If I was going to buy a super-lightweight 2-seater, it'd be a Noble M12 GTO, no contest (the new M400 model)
0-60: 3.5 secTop Speed: 185mphBetter skidpad than a McLaren F1425hp w/2300lb curb weightGetrag 6-speedExceedingly snazzy interior (better than most production cars).
All for about $70,000 or something like that. With a little more work done to it, you'd have something that would run easily with an Enzo and McLaren F1 in any category but top speed.
http://www.noblecars.com I do NOT work for them or anything, I'm just completely obsessed with these things.