Trucks can use all sorts of engines. Small trucks such as SUVs or pickups, and even light medium-duty trucks in North America and Russia will use gasoline engines. Most heavier trucks use four stroke turbo intercooler diesel engines, although there are alternatives. Huge off-highway trucks use locomotive-type engines such as a V12 Detroit Diesel two stroke engine.

North American manufactured highway trucks almost always use an engine built by a third party, such as CAT, Cummins, or Detroit Diesel. The only exceptions to this are Volvo and its subsidiary Mack Trucks, which are available with own engines. Freightliner, Sterling Trucks and Western Star, subsidaries of DaimlerChrysler, are available with Mercedes-Benz and Detroit Diesel engines. Trucks and buses built by the Navistar International can also contain International engines. The Swedish truckmaker Scania claims they stay away from the U.S.-market because of this third party tradition.

In the European union all truck engines must comply with Euro 4 regulations, the regulations will become more restrictive in 2008 with the introduction of Euro 5.

Formerly in Britain some lorries were coal-fired steam-powered: for more information see Traction engine.