My view on carbon emmisions and the hate some people aim at owners of cars with big engines is that everybody should have a carbon allowance.
I know many people who like V6's, V8's and straight sixes. Most only use them for pleasure use so do not cover vast mileage so it is not as bad as your average shopping trolley being used everyday even for uneccessary journeys.
What you tend to find are people who might have a car which doesn't pollute quite as much as a V8 for example but have the central heating on 24hrs with the thermostat set at 25 degrees C.
If we all had a carbon allowance, you could turn the central heating down or off and go for a ride in your 6 litre V8