bah this hybrid stuff is nonsense. good fuel mpg's are nothing new. my '79 vw diesel 5spd was built like a tank and got over 40mpg's highway...
with the extra fuel tank in the back it could go over 1000 miles without filling up... i bought for 1500 bucks...
if it wasn't for a cracked block i probably would still have it today....but still drove it close to 200k miles.
point is the technology for fuel efficiency isn't anything new.
and no you don't drop 2000 lbs of gravel in the back of a small car ..for that you need a nice pickup (a ford preferably, lol)..
if you want to be real green get a W123 model mercedes diesel and run it on waste veg oil.
here's good little video
http://www.volksfolks.org/gallery/commercials/rabbit/problem.html