To understand why Detroit is at last taking energy efficiency seriously, it helps to look into the eyes of Tom LaSorda. I had lunch with Chrysler's affable chief executive last week at the Detroit motor show. It was a memorable occasion.

Mr LaSorda is on the rack. He over-estimated the number of Chrysler cars and trucks that Americans would buy last summer, as petrol prices rose sharply and put many people off the gas-guzzling pick-ups and sports utility vehicles that make up 71 per cent of his line-up.