EPA website rates greenest vehicles
 

The vehicle history only goes back to 2000. But its a nice site for comparing impact of vehicles.

My 99 Contour 6 cyliner automatic DOHC on a scale 1-10, 10 being the highest:
1 for air pollution (ugh!)
5 for greenhouse gas (see comments on 1)

Thats figurung with a 19 mpg avg fuel economy for my car. With your guys help I've gotten up in the 30's. So I'll bet I would show a little higher than a 1 and 5.

Anyway take a look at the site, its pretty neat.

http://www.epa.gov/greenvehicles/Index.do

The scales starts at 0...
...at least that's what my TDI gets for air pollution.

On the other hand I get a 9 for greenhouse gas.