Know the Difference Between AWD and 4WD
A growing number of vehicles sold in the U.S. are equipped with all-wheel drive (AWD) or four-wheel drive (4WD)—45 percent, in fact. Obviously, these features are popular with buyers, but that doesn’t mean these upgrades are universally a good match for every driver, every vehicle use, and every driving condition. If you’re considering a vehicle with AWD or 4WD, here’s what you need to know to make a smart auto buying decision.
All-wheel drive means power can be sent to both the front and rear wheels, as opposed to front- or rear-wheel drive, where only one set of wheels receives power. How often both sets of wheels are engaged depends on the type of AWD: full-time or part-time (sometimes called automatic) AWD.
Full-time AWD delivers power continuously to all four wheels. When driving on dry pavement, this can give a smoother ride and offer tighter handling. Under slippery conditions—including ice, snow, mud, and rain—it provides additional traction for safer driving.
Part-time AWD operates most of the time in two-wheel drive (2WD) mode—either front or rear, depending on the vehicle—only delivering power to both wheel axels when sensors say additional traction control is needed. This can save on the vehicle’s miles per gallon (MPG).
AWD appeals to many drivers because it doesn’t generally require any input by the driver to decide which wheels get more power and when; it’s decided by the vehicle’s computer, based on input from system sensors. The driver doesn’t have to think about engaging the system and can concentrate on the road and other cars around them. Some systems offer selectable modes that give a certain amount of control to the driver over how much power goes where. If you’ll be driving over rapidly changing road surfaces, for example from soft snow to hard-packed snow to ice, an AWD system is best at dealing with these shifting conditions.
AWD is available on a wide variety of vehicles, including compact sedans, performance cars, family and midsize SUVs, crossovers, and trucks. It does, however, increase the cost of a vehicle and reduces its fuel economy. Overall repair costs are also higher because there are more parts that may need repair.
Heavy-duty vehicles with high ground clearance, shielded underbodies, tow hooks, and big tires are more likely to offer 4WD. This system of traction control and handling is found primarily in large trucks and SUVs used for work and play on difficult terrain and road conditions.
Although 4WD operates under the same principles as AWD—including with part- and full-time modes—it can generally handle more rugged terrain and heavier towing capacities on slippery surfaces and is initiated by the driver instead of a computer. A 4WD system has low and high ranges that can be chosen by the driver via a switch or floor-mounted lever. The low setting is used for maximum traction in off-road environments. The high setting is the default configuration and ideal for compromised on-road conditions like packed snow and ice, and loose sand or gravel. Overall, a 4WD vehicle is better suited to navigating deep snow, easing out of snowdrifts, and managing icy hills.
A word of caution for those considering a 4WD vehicle: if you don’t pay close attention to the driving surfaces and adjust the 4WD settings appropriately, you may experience a shuddering sensation caused by wheel wind-up. This could damage your vehicle’s differentials and axles. Buyers can expect to pay more for a 4WD vehicle—in purchase price, fuel consumption, and repair costs.
Regardless of a vehicle’s AWD or 4Wd capabilities, drivers should still handle their cars defensively and responsibly in adverse conditions. Neither wheel-control option helps you stop better in slick conditions.