I have a green car. Well it's a mica black Daihatsu new Sirion 1.0S actually. It's green because it gives off 118g CO2/km, which means next year's car tax is a mere £35. This is seriously good, and nearly as good as the much touted hybrid Prius. However, you don't need to go hybrid to go green - VW have just announced a diesel Polo with 102g CO2. Pity they couldn't get it under 100, as tax would then be free!
Trouble is, there is no concensus on green cars (or anything else environmental). Apparently if you take the total carbon footprint from design, development, manufacture, usage through to scrapping, the picture changes, Jeep even claim some of their models to be high on the list. I'm confused and probably ought to cycle more. I keep switching stuff off, though!