Finally got time and inclination to do a complete underbelly on my silver Insight. I used aluminum in the front and rear, where there is some heat, and 4' coroplast sections in the middle of the car. I was interested in measuring the diffuser angle at the rear and providing a flat diffuser section made that possible. Using my gravity type level gauge I got a number of 4 deg.+/-, which is near ideal according to Hucho; The diffuser begins just slightly in front of the rear wheels.
As an interesting asside, the Insight will roll on a 1 deg. slope.
I'm now looking at starting a boattail
Probably a winter project, if indeed I can get the time from my other projects. Need to go back and read some of that early design stuff on 3 Wheeler's design thread. The scholarly paper of the Swedish graduate students arrived just a bit too late, but it should make good reading.
EDIT: photos added in post #17 -
http://ecomodder.com/forum/showthrea...tml#post319036