The plans say it gets up to
125 miles per gallon.

I keep kicking around the idea of making a one seater car
out of a small motorcycle drivetrain. Can't decide how to go about
it though. I've considered a trike-car, but I think a trike wheel in
the
front would be too unstable. Not sure about a rear steer trike.
Also have kicked around the idea of just adding frame to one
side and making a four wheeler motorcycle, but with only one
side actually driving power. I'd like to make a light glass
body that looked like the front of a jet plane, to cut wind
resistance. If you used a 125-250 cc range engine, I bet
you could get pretty a pretty decent mpg. Being I once had a
yamaha 250 that probably did 80-90 mph, I think going street speeds
would be a snap. Dunno how if would fare on the freeway...
Could probably do 55 I bet if stable enough.
MK