Four wheel drive. In most of the world refers to cars with a transfer case or a differential in the center. In the USA, applies only to vehicles with a center transfer case (compare all wheel drive or "AWD".)
The Hummer H2 is a brilliantly-marketed sort of baby huey version of a [[Chevrolet Tahoe]]. [[General Motors]] ([GM]) owns [[AM General]], which makes the [[Hummer]] [[SUV]], which is in turn just a civilian model of the military [[HMMWV]] vehicle.