[elhigh]

Well, this contest is already won. Somebody just needs to roll up in a Quickie II. If I recall correctly - and this is information I'm trying to dredge up from the 80s, so bits may have fallen through the flashback holes - the Q2 delivered over 80mpg, carried 2, and cruised around 135mph. The prototype used a two-cylinder engine cut down from a VW 1600. It wasn't a fast plane by any means, but I don't care how you measure, if you can average over 100mph in a straight line vs. 60mph on roads, you're gonna get there sooner.

Did somebody at NASA totally forget that people having building planes for a long time? There's a lot of really thrifty models out there. How about a Cessna 182 RG (my personal favorite, one of the most attractive highwing designs I've ever seen) - I think it'll carry four and deliver 30mpg - that's 120 passenger miles per gallon.