We learn from Sustainability Zone that the British Toyota Website lets you graphically compare greenhouse gas emissions of various models. Now we can test a pet theory- that a small, economical car with a small, conventional engine is better for the environment than a Prius. The Prius emits only 104 grams of CO2 per km driven, whereas the Yarus (looks like an American Echo) emits 117 gm/km. Winner: Prius.
However, the Prius weighs 290 Kg more than the Yarus/echo. In our quick, dirty and not very scientific analysis we assume that the difference in weight is steel (it's probably batteries but give us a break) and knowing that making a ton of steel emits half a ton of CO2, 145 extra kg of CO2 were emitted while making the Prius.
Divided by the difference in emissions while driving, one has to drive 11,153 km or 6,930 miles before the Prius steps ahead, but step ahead it does in a reasonable amount of time.
Of course, if one factors in the greenhouse gas emitted earning the extra $ 15,000 it costs to buy the Prius, this may be another story.... [by Lloyd Alter]