Since I'm actually supposed to "work" tonight, I just did a search and guess what??? Apparently there was a Hybrid race car in a 24 Hour race at the Nurburgring track last year!
Civic Hybrid completes 24-hour race | Car Tech: An automotive blog from CNET
So, instead of bolt-ons, may be go the weight-savings route and tell your friend to remove the seats, liners, AC, radio, carpets, replace windows/windshield, etc., and if he's heavy...hit the treadmill
EDIT: Here's a link to a better pic of the hybrid race car.
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