The New York Times reports that Ford has agreed to use a diesel engine designed by the EPA in new-generation cars and trucks. Diesel is generally a more efficient fuel (around 30% better than gasoline), but it has had problems in the past with particulate and nitrogen oxide pollution. Cleaner diesel engines now power about half of the cars sold in Europe, but are only a small fraction of vehicles in the US. The new engine, designed by the US Environmental Protection Agency, runs clean enough not to require special filters, meaning that it should have a low production cost. I suspect Mike will have more details about this in his Sustainability Sundays post.