> I'm not sure an environmental conscience is the reason, rather the cost of keeping your car taxed and insured, then finding somewhere for it to stay in London

> I'm not sure an environmental conscience is the reason, rather the cost of keeping your car taxed and insured, then finding somewhere for it to stay in London, and then finding a use for it, outweighs simply using public transport. That's (part of) the reasoning behind car tax, petrol tax, etc.: to turn vague, idealistic goals (environmental concerns, efficient public transport rather than umpteem invididual cars, etc.) into concrete economic decisions. The problem arises when these start to be abused, e.g. getting more people to drive in order to raise tax revenue ;)