Some car companies -- like General Motors -- think Americans might be ready to buy more diesel cars, as gas prices rise.
GM will offer a diesel version of its Chevy Cruze in the U.S. next year.
Early diesels in the U.S. had performance problems, like engine knocking.
But Charlie Klein of GM says modern diesel engines are dramatically better than in the past.
"Those that have driven them, they are terrific to drive," says Klein. "And of course they deliver terrific fuel efficiency."