Diesel cars get great fuel economy, which you probably know if you’ve rented a car in Europe recently. Most of the cars rented there are diesels. The problem with diesel has always been pollution – until now. Mercedes has come up with a technology that makes the fuel burn cleaner than a gas engine would. The new fuel and new engine allow these diesels to get 40 percent better fuel economy. They get 20 mpg as a gas car and 28 mpg as a diesel car. The smaller the car gets, the better the fuel economy. Clark thinks this effort will be successful and other companies will follow suit.