London ? Mayor Ken Livingstone, a self-admitted hater of automobiles, is planning to lower the boom on American-style sport-utility vehicles and other gas guzzlers by charging a $50-per-day “green tax” for the privilege of driving in the center of London.

Even those who can afford the $140,000-plus it costs to own a top-of-the-line Range Rover Vogue or a Porsche Cayenne Turbo are swallowing hard at that one.

Livingstone disdainfully refers to such vehicles as “Chelsea tractors” – a reference to the posh London neighborhood where they seem to be most popular – and to their affluent drivers as “complete idiots.”