I read a study once (cant recall where) which looked at the environmental impact of all sorts of cars, and the result (which, of course, could be bent) was not what you would expect.
The car they concluded was the 'greenest' motor was not a modern hatchback, or a prius, or some other sort of hybrid, but an aged **** <name edited out.
They figured that, although the mpg wasnt great, the design was simple, and sturdy, the environmental cost of production low, and the expected lifespan much greater than many other vehicles.
People all too often overlook that the environmental cost of something is not just the running cost, but the huge costs in its production.
So, what did they think was the most environmentally sound car?
Im not going to tell you.
(pete would never let us hear the end of it!)