We can't do much for the frontal area but I have played with ideas of how to
reduce the Cd. I've considered casting hundreds of urethane (glass-bubble
filled to be lightweight) semi-spheres (imagine a .25-375" section off the
edge of a 6-8" diameter sphere) and gluing them in a pattern on the rear
1/3rd of the vans sides and roof.
You'd have to play with sphere size and spacing but this would effectively
reduce the Cd of the van by breaking up the vortex in the rear.

This would work especially well for someone going with a polka-dot theme on
their van.

By the way, if a sphere is .2'ish then what is a golf ball? A golf ball has
a much lower Cd than a sphere of the same size. Yes? (BTW- I'm not a golfer,
just part Scott)

-Steven Dodson
Kneeland, CA
"Inga" the 87 Syncro