Diesel, once long ignored like the ugly stepchild of the fossil fuel family, has worked its way out of the dirty dungeon and made it to the ball. As in the Cinderella fairy tale, diesel's fairy godmothers, the auto industry and oil companies, have transformed it from a grimy, smelly mess into a serious contender for Prince Charming's hand. More importantly, fuel-efficient diesel vehicles are now serious contenders for Americans' garages, as buyers seek out the most painless solutions to high gas prices that aren't going down anytime soon.The change from social outcast to debutante was not an easy one, but diesel may soon have many American suitors. Why? Today's diesel engines provide 20-to-40-percent better fuel economy and offer more torque at lower rpm when compared to their gasoline counterparts. Diesel engines are also substantially less harmful to the environment today than they were in the past — and are headed down the road to becoming even cleaner in the near future. While some automakers don't have plans to offer diesels in light-duty passenger vehicles just yet, all of the major manufacturers are taking a serious look at the technology.

Why Diesel? There's a powerful impetus for the government to encourage diesel-powered vehicles in the United States: It would reduce our dependence on foreign oil. Of all the types of internal-combustion engines, the diesel engine is the most efficient: A given amount of diesel fuel can make more power than the same amount of gasoline. (For an overview on the diesel engine, read How Hybrids and Diesels Work.)