What 4WD Means:
Four-Wheel Drive (4WD). Four-Wheel Drive is a selectable system; that is, a 4WD vehicle can be operated in 2- or 4WD, depending on the driver's preference. 4WD refers to a two-axled vehicle drivetrain capable of providing torque to all its wheels simultaneously. It may be full-time or on-demand and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges. In contrast, a vehicle with an All-Wheel Drive constantly sends power to all four wheels.