Car industry's green push challenged by low petrol prices

Detroit

BENEATH the hoods of the cars showing in Detroit this week lie engines that are as powerful as ever, but are smaller and, helped by direct injection, guzzle less petrol.

Carmakers have subbed out stainless steel for aluminium and other lighter-weight materials, and added more gears to let engines run in "sweet spot" mode more often so that their cars and trucks can save money on fuel and emit less climate- harming pollutants.