A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration; smaller varieties may be mechanically similar to some automobiles. Commercial trucks can be very large and powerful, and may be configured to mount specialized equipment, such as in the case of fire trucks and concrete mixers and suction excavators. Modern trucks are largely powered by diesel engines, although small to medium size trucks with gasoline engines exist in the US, Canada, and Mexico. In the European Union, vehicles with a gross combination mass of up to 3.5 t (7,700 lb) are known as light commercial vehicles, and those over as large goods vehicles.