One of the aspects that makes diesel engines attractive is high thermal efficiency which can be as high as 54%, compared to the 34% average efficiency of spark-ignited gasoline engines. Diesel fuel differs from gasoline in several ways. Diesel fuel is heavier and oilier than gasoline. It evaporates much more slowly because it is composed of larger hydrocarbon molecules, which have higher boiling points, typically 150 °C to 370 °C.
