4 X 4 four weahel drive is a four-wheeled vehicle with a drivetrain that allows all four wheels to receive torque from the engine simultaneously.
While many people typically associate the term 4×4 with off-road vehicles and Sport utility vehicles, powering all four wheels provides better control than normal road cars on many surfaces, and is an important part in the sport of rallying.
In abbreviations such as 4×4, the first figure is normally the total wheels (more precisely, axle ends, which may have multiple wheels), and the second, the number that are powered.
Syntactically, 4×2 means a four-wheel vehicle that transmits engine power to only two axle-ends: the front two in front-wheel drive or the rear two in rear-wheel drive.
By this system, a six wheeled military transport truck would be a 6×6, while the typical American semi-truck tractor unit having two drive axles and a single unpowered steering axle would be a 6×4.