A sport utility vehicle (SUV) is a generic marketing term for a vehicle similar to a station wagon, but built on a light-truck chassis. It is usually equipped with four-wheel drive for on- or off-road ability, and with some pretension or ability to be used as an off-road vehicle. Not all four-wheel drive vehicles are termed as SUV. Some SUVs include the towing capacity of a pickup truck with the passenger-carrying space of a minivan or large sedan. Since SUVs are considered light trucks and often share the same platform with pick-up trucks, they were regulated less strictly than passenger cars under the two laws in the United States, the Energy Policy and Conservation Act for fuel economy, and the Clean Air Act for emissions. Starting in 2004, the United States Environmental Protection Agency (EPA) began to hold sport utility vehicles to the same tailpipe emissions standards as cars.