An all-wheel-drive system powers all four wheels of a vehicle simultaneously for improved handling in slippery conditions. 

Typically, AWD systems function using a series of clutches that connect the front and rear axles, controlled by a computer that monitors traction levels. 

Two types of AWD systems exist: part-time and full-time.

Full-time all-wheel drive continuously powers both axles and all four wheels, with some systems varying torque levels depending on driving conditions.

Part-time all-wheel drive primarily drives either the front or rear wheels, and when slippage occurs, it sends engine power to the other axle for additional grip. 

Besides extra traction in snowy weather, full-time AWD can also improve acceleration and cornering on dry pavement because it routes more power to the road. 

Part-time AWD is a reactive system that depends on sensors observing wheel slippage to activate fully. Because part-time AWD systems usually only power one axle, they may offer improved fuel economy versus full-time versions.

One major plus about both types of all-wheel-drive systems is they function autonomously, without the need for driver input. So if snow begins to fall or the road becomes icy, all you have to do is drive and let the AWD system take care of the rest. 

However, some AWD vehicles have separate traction control modes like “snow” and “ice,” which give added assistance when roads become hazardous. 

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Even though all-wheel drive and four-wheel drive may sound like the same thing, they function differently.

Typically found on pickup trucks and SUVs, 4WD systems are a burlier alternative to AWD ones. That's because automakers design 4WD components for rugged terrain that requires additional robustness.

Like all-wheel drive, four-wheel drive comes in two varieties: part-time and full-time. 

On a part-time 4WD vehicle, the engine powers the rear wheels during regular driving. But when conditions mandate, the driver can pull a lever or press a button to send power to the front axle. 

Full-time 4WD cars power all four wheels continuously for maximum traction and grip in all conditions. On some four-wheel-drive versions, the driver can vary the power distribution between axles to influence handling characteristics. 

Frequently, four-wheel-drive drivetrains feature a low-range and a high-range, which the driver selects. The low range setting is for particularly demanding situations, like off-roading when you need maximum traction. The high range setting is more suited to driving on regular roads and highways.

No matter what type of drivetrain your vehicle has, ice and snow are among the most hazardous conditions to drive in. And even though AWD and 4WD increase traction, snowy weather still requires caution, and you may experience increased braking distances and slippery handling.

Usually, 4WD offers the best traction in the most demanding conditions like deep snow or icy inclines. With its burly construction and user-selectable ranges, four-wheel drive is comfortable in the harshest road conditions. 

But for everyday driving and in climates that undergo quick weather changes, all-wheel drive is an excellent choice. Because of its computer-controlled design, an AWD drivetrain takes care of the decision-making for you, varying torque splits between axles as conditions require. And since many all-wheel-drive systems have snow or ice settings, you have an additional layer of security when the weather turns bad. 

Aside from whether a drivetrain's AWD or 4WD, its specific design also impacts traction. 

Part-time and full-time all-wheel-drive systems may vary significantly in available traction and road-holding due to their particular qualities, like the torque split or differential design.

And some 4WD drivetrains are particularly stout with locking differentials in the front, rear, or center for the ultimate grip.

4WD and AWD drivetrains both provide power to all four wheels, but they differ in function and levels of traction.

Part-time AWD systems typically drive two wheels on either the front or rear axle and activate automatically when a computer detects wheel slip. Full-time AWD drivetrains are always on, powering all four tires for enhanced handling during both dry and snowy conditions.

Initially designed for pickups and SUVs, 4WD setups offer more burly components for off-roading or deep snow and are the better choice when driving in especially poor conditions. 

Drivers activate part-time 4WD systems via lever or button and, in some cases, can select a low-range or high-range setting depending on terrain. And some vehicles offer the advanced 4WD technology of a driver-selectable torque split front to rear. 

Whether or not four-wheel drive or all-wheel drive works better on snowy roads depends on the driver, particular drivetrain design, and local weather conditions. Either type offers enhanced traction, safety, and security when encountering winter weather. 

When you buy a used all-wheel-drive vehicle, you want one that lasts. After all, you don't want to drive through snow and ice and experience mechanical issues. But with Shift's best-in-industry service contracts, you have peace of mind no matter where you drive. With a Shift Vehicle Protection plan, not only are essential components covered, but you also receive roadside assistance if you run into trouble away from home. Wherever you happen to be in the continental US, Alaska, Hawaii, or Canada, help is just a toll-free phone call away, 24 hours a day, seven days a week, 365 days a year. And when you need to finance, we have that covered too. Shift works with a network of trusted lenders who compete for your business, so you get the best deal on financing.