Compare a single Prius and a single H3:
More polution was created during the production of a Prius than the total emissions from an H3's tailpipe.
On the referenced web site:
http://www.terrapass.com/
If they really cared about polution... Why does the car in the background have mirrors (could be cameras instead), a big antenna (could be a internal windshield antenna), and a roof rack to increase aerodynamic drag which uses more fuel and more CO2 emissions. How about their shoe soles - they look tlike they're made from natural products. How about the dude's watch - doesn't look solar powered to me - where's he put the dead watch battery? How about the stuff in the dude's hair - was propane the propellant in the hair spray stuff?