I'm sure that Jeremy Clarkson had absolutely no proof when he made that statement that a Prius pollutes more than a Land Rover Defender. However, if you think about it: How much pollution is caused by the ship going across the ocean from Canada to Japan with the Nickel, and then how much is created by the ship going from Japan to the UK with the Prius aboard. Those are 2 very long (and polluting) ocean journeys the Land Rover and its components didn't have to make. I guess I wouldn't be surprised if the net total polution is greater for a Prius than a Defender at least up to a certain mileage point.