Most vehicles use two-wheel drive (2WD), where engine power is brought to either the leading or rear wheels only. Front-wheel drive is used generally in mostwagons and cars, and minivans because it’s space-efficient. It allows a smaller engine compartment, leaving more room inside for passengers and cargo. It’s also a lot better than rear-wheel drive in slippery conditions because there’s more weight on the front drive wheels and the wheels pull as an alternative to push the auto along the road. This helps prevent the vehicle’s rear end from sliding sideways in slippery conditions.
Rear-wheel drive places less demand on the front wheels, letting them be used primarily for steering. It’s frequently used on pickups and traditional, truck-based SUVs that are designed to handle heavy-duty chores such as towing. But rear-wheel drive can also be popular on sports cars and high-performance sedans because of its contribution to good handling.
Traction control, available on many two-wheel-drive vehicles, helps maximize traction in the drive wheels by preventing wheel spin. It’s particularly useful starting on asnowy and wet, or icy surface. If neither drive wheel has grip, however, traction control won’t help. In wintry conditions, we’ve found that all- or four-wheel drive is better than traction-control alone for obtaining up a slippery slope.
All-wheel drive (AWD) feeds power to all wheels. It gives maximum forward traction which is especially helpful in wintry conditions and when driving over moderate off-road terrain. AWD systems are especially useful when you are rapidly changing conditions or when driving with a road with intermittent ice and snow. Its lightness and compactness makes AWD the device of choice for wagons, some minivans and pickups, and most car-based SUVs. (See our list of best AWD vehicles.)
The limitations of all the- and four-wheel drive often go unappreciated. If you’re going inside a straight line but does nothing to improve braking or cornering, capacity to all four wheels helps. Thus, such systems don’t let you drive exactly the same or in the same speed as you would on a dry road.
Although four-wheel drive (4WD) and AWD are designations which can be often used interchangeably in sales and advertising literature, the important thing difference is the fact that 4WD incorporates low-range gearing, which, when selected, assists in more challenging off-road conditions, for example climbing over boulders, fording deeper water, or tackling steep off-pavement hills. The majority of 4WD-vehicle owners, however, never come close to needing this capability. 4WD systems will also be more expensive, more difficult, and heavier, which compromises fuel economy.
Modern 4WD systems may be full-time, which implies they can stay engaged constantly, or automatic, where the vehicle automatically switches between two- and four-wheel-drive mode, depending on the driving conditions. Many pickups and a few truck-based SUVs, however, have only part-time 4WD systems. These require the driver to manually shift between two- and four-wheel drive, which limits the vehicle’s capacity to provide optimum traction once the road surface suddenly becomes slippery.
For rain and incredibly light snow, 2WD will probably work fine. Front-wheel drive with traction control is the preferred setup. AWD would provide an additional margin of safety. AWD is also acceptable for most normal snow conditions or for traveling on dirt roads without high rocks, deep sand, or steep inclines. You should go for 4WD if you’re going where you’ll encounter more-severe conditions.
Additionally, a vehicle with a part-time system can’t be driven on dry pavement when in 4WD mode without running the risk of severe injury to the vehicle’s drivetrain.
Remember that both AWD and 4WD systems add considerable weight to a vehicle, compromising fuel economy. See our list of best off-road vehicles.
The myth of 4WD
One of the reasons a lot of people buy a traditional sport-utility vehicle is for the extra security and traction of four-wheel drive. But for most drivers, 4WD may be overkill. The type of vehicle that’s best for you depends on the kinds of conditions you typically face. For rain and light snow, two-wheel drive will probably work fine. Front-wheel drive with traction control is preferred. AWD is fine for normal snow conditions or perhaps for traveling on packed sand or dirt roads. For more severe conditions, you should select 4WD.
Furthermore, a common misconception is that 4WD and AWD systems assistance in all driving situations. In reality, those systems provide added traction only when accelerating. They generally do not help in braking or cornering.
Drivers often make your mistake of utilizing less caution when driving in slippery conditions with a 4WD vehicle, and they pay for the consequences by sliding off of the road and often rolling over. Drivers should be more vigilant, not less, because the added traction of 4WD can allow a vehicle to accelerate more quickly in slippery conditions. For extra assist in braking, get yourself a vehicle with antilock brakes. For a cornering aid, try to find an electronic-stability-control (ESC) system. But neither of these systems can overcome the laws of physics. Slippery conditions demand extra caution, no matter what you drive.