According to the U.S. Department of Energy, diesel engines have greater fuel efficiency than gasoline engines of a similar size. Diesel vehicles can go roughly 20 to 35 percent farther on a gallon of fuel than gasoline vehicles because diesel fuel contains more energy than gasoline.
Diesel vehicles of 2015 are considered far superior to diesel vehicles of the past. For example, Insider Car News rated the 2014 BMW 328d its most fuel-efficient diesel car, with an impressive combined miles per gallon of 37. While not all diesel vehicles get this kind of mileage, diesel vehicles now compare quite favorably to gasoline ones.