How on Earth can an enormous Ford Expedition with a 5.4 litre engine get the emissions as a normal sedan (unless it was a big Cadillac or something)? You'd be wasting your time trying to find out whether other SUVs don't pollute more than medium-sized cars (and when I say medium-sized sedan I mean something like a VW Passat not a 4 litre Buick or Chevy), because in general THEY DO. Explorer4x4 used to spend ages going on about the fuel economy of SUVs but his argument held no water, all the factory test results that he quoted were not realistic measurements of the fuel economy SUVs gets when they are driving around on real roads, through real cities instead of some test lab. America's idea of good fuel consumption is about 20-25 mpg, where I come from that's a bit thirsty. But it's alright for Americans to have thirstier cars because they pay half as much for gas as we do.

It doesn't matter anyway, the huge growth in air travel is doing far more harm to the environment than cars.