ALL WHEEL DRIVE (AWD) VS. 4-WHEEL DRIVE (FWD)
All-Wheel-Drive: AWD systems deliver power to each corner of the vehicle, similar to 4WD cars. However, unlike 4WD cars, AWD is always engaged and provides varying amounts of power to the axles depending on traction conditions. All-wheel drive systems primarily power one set of axles, either front or rear. When the car feels traction loss in one axle, it will automatically divert more power to the other axle to compensate. Not all AWD systems utilize the same power ratio. For example, Subaru’s all-wheel-drive system continuously sends at least 20% of the engines power output to the rear axle, with the possibility of directing more if necessary. Other systems exclusively power the front axle and only rebalance engine output to the rear when the front tires are losing traction.
AWD cars work well in moderate off-road driving situations, or when driving conditions are prone to change due to terrain variation or volatile weather conditions. In addition, AWD vehicles provide great overall traction during acceleration due to all four wheels being engaged. AWD systems are commonly found in car-based SUVs and minivans, but also often make an appearance as an option for performance rear-wheel-drive cars.
Four-Wheel Drive: Four-wheel drive (4WD) cars are generally tuned for extreme off-road uses like traversing over deep water, scaling boulders or climbing steep hills with poor surface traction. When enabled, 4WD systems send power to all four wheels using front and rear differentials plus a transfer case that distributes power equally regardless of traction. In addition, some 4WD have two gear ranges, high and low. The low gear range proves especially helpful when low-speed climbing power is required. There are three different mode toggle options in modern four-wheel drive vehicles. Full-time systems are always engaged, automatic systems switch between 2WD and 4WD automatically, and part-time systems require the driver to switch between two-wheel drive and four-wheel drive modes manually. Driving a part-time 4WD vehicle on the pavement with 4WD enabled can cause damage to the vehicle’s drivetrain.