ratty said:
popuptoaster said:
if your engine is throwing unburnt fuel down the exhaust, it wont produce co2 from that fuel, but the unburnt fuel will still reduce your mpg, so worse economy does not automatically mean higher co2.Unburnt fuel will evaporate and release CO2 etc
I take your point though, but if both engines are running properly then MPG should equate to CO2 emissions. 2 cars with 30mpg should produce the simular amount of carbon.
What you drive though is less important to how you drive though if talking about emissions and as such any green tax should be on fuel
as i said its down to design, some engines use the fresh charge of air/fuel to push the exhaust gasses out the exhaust and so they lose some of it with the exghaust gasses, also some engines do not always burn the complete fuel charge at some revs, valve overlap plays a big part, although they all work pretty much the same the little differences are still there.
obviously most modern engines are set up for low co2 and high mpg, but there are a few suprises in the co2 bands.