The Difference Between All Wheel Drive (AWD) and Four-Wheel Drive (4WD) Explained.

There are many choices when it comes to picking your next vehicle. Understanding the difference between an All-Wheel Drive (AWD) and Four-Wheel Drive (4WD) car, truck, or SUV will help you decide which system best meets your needs.

While the terms AWD and 4WD are often used as if they are interchangeable, there are real and important differences between them.

Typically found in off-road or all-terrain vehicles, 4WD (also sometimes called 4x4 or four by four) gives the truck or SUV the ability to move efficiently over slick or slippery roads. It also gives the vehicle enough power to climb over nearly anything in its way, depending the height of the obstacle. Driving over low traction surfaces like mud or sand, steep hills, standing water, and even climbing boulders usually requires a 4WD system.

Full-time 4WD and part-time 4WD

Unless there is some serious off-road driving in the future, a 4x4 or 4WD system usually isn’t necessary for everyday driving. Many vehicles with 4WD capabilities are part-time systems, so the driver can switch between 2WD and 4WD, depending on the driving conditions.

Full-time 4WD systems are on all the time. In some vehicles, the switch between 2WD and 4WD is automatic, so the driver never makes the decision about which mode is most appropriate in each situation.

People considering a part-time 4WD system should understand that driving on dry pavement in 4WD could damage the vehicle’s drivetrain. Driving at high speeds in 4WD may also cause unnecessary stress on the truck’s mechanical systems.

4WD and traction

While it may seem like driving in 4WD mode 100% of the time would offer the maximum amount of traction, that isn’t true in all cases. When the vehicle is in 4WD, the transfer case splits the power distribution between the front and rear axles evenly. When turning, this even power split prevents the inside wheel from turning more slowly than the outside wheel, and could cause the inside wheel to spin.

For this reason, part-time 4WD vehicles offer the greatest degree of flexibility and a best-of-both-worlds situation for the driver. Under normal conditions, 2WD allows the car to turn while maintaining traction and drive at higher speeds without breaking mechanical components. Cars in 2WD also get better fuel mileage.

Some advanced systems have a driver-regulated 4WD High and 4WD Low option. Mud, sand, or snow causes problems for regular vehicles, but in 4WD Low mode, these conditions are easy to handle at slower speeds.

4WD High mode allows limited slip between the wheels while still splitting power evenly between the axles. This prevents the problem with locked or spinning inside wheels, but is really only appropriate during higher speed driving conditions.

AWD and traction

For added stability in weather-related hazardous conditions, AWD offers the most versatility and potential for traction. An AWD system is always on, so the driver doesn’t need to make decisions about which mode to use and when.

AWD systems aren’t usually as tough and don’t offer as much traction at low speeds as 4WD systems. However, in challenging weather, an automatic system like AWD responds faster than most drivers can to rapidly changing conditions.

An AWD system feeds power to each individual tire. This provides the driver with maximum traction while they are attempting to accelerate on a sloppy road or during heavy precipitation. The system decides which axle needs the most power, and if it detects slippage, it diverts some power to the other axle to correct the unwanted spinning or sliding.

In most AWD systems, 100% of the power is behind the front wheels until the situation calls for additional help from the back wheels. Certain car models, crossover vehicles, and minivans are equipped with AWD systems. Drivers of this type of vehicle like the reliability of the AWD system, especially in weather conditions that include intermittent ice and snow.

Making the choice between driving a AWD vehicle and a 4WD vehicle really comes down to where the driving occurs. Highway and in-town driving in slick, snowy, and rainy conditions demands an AWD set up. There’s no need to manually switch between two-wheel and four wheel or choose a low or high mode with the automatic AWD configuration. That makes day-to-day driving easier.

The 4WD system has been around for more than 125 years. It’s simple, gives the driver control over which mode to use depending on the situation, and is tough enough to handle off-roading challenges. For rock crawling, deep snow, sand, and mud, the 4WD system is a natural choice.

While there are some additional variables that exist inside the 4WD option, if you decide 4WD is the right choice, choosing a center locking differential versus a locking rear differential is much easier.

 

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