Could diesel help in energy pinch?

A few years ago, it looked like diesel engines would undoubtedly play a substantial role in the looming fuel crisis -- which, of course, arrived with a vengeance that few of us anticipated. Almost weekly, I'd get a call or a letter or an e-mail from a reader who had just returned from Europe, drove some diesel-powered vehicle that performed well and got exceptional mileage, and wondered why that power plant wasn't available here. The answer five years ago was pretty easy: Six states, including California and New York, had tougher anti-pollution laws than the federal government's, which essentially banned the sale of diesel engines in new cars.