All-Wheel Drive Vs. Four-Wheel Drive: Defined And Explained

When you think of vehicles toting all-wheel drive or four-wheel drive capabilities, you probably imagine work trucks or full-sized SUVs built to handle the toughest off-road adventures. While these features are still popular in trucks and full-sized SUVs built for going off the beaten path, they’re now also prominent in many makes and models of cars found on the (paved) road.

Today, drivers searching for vehicles that can handle challenging, slippery conditions like snowy, icy or mud-covered roads rely on AWD or 4WD options. Gone are the days when these systems were only used for heavy-duty situations.

Due to advancements in both traction systems and the modern car overall, understanding AWD vs. 4WD can get a little confusing. Knowing how the two systems differ and the pros and cons of both can help you decide which system is best for your lifestyle.

On the surface, the difference between AWD and 4WD typically comes down to the types of conditions the car can best handle, as well as driver involvement in controlling the torque being sent to the wheels.

Both AWD and 4WD systems deliver torque to all wheels to increase traction and decrease slippage, which is what makes distinguishing between the two so difficult. But, each system is beneficial for different terrains or driving conditions.

In most modern cars featuring an AWD system, the car will vary the amount of torque being sent to each axle and wheel based on sensors, requiring no involvement from the driver. All-wheel drive cars are perfect for every day and all-weather driving conditions, performance driving and some light off-roading adventures. This system is ideal for rapidly changing conditions since it is all computerized and doesn’t require driver input.

In a 4WD-equipped vehicle, the driver can usually decide when to engage the system through the push of a button or pull of a lever, although some 4WD systems operate in 4x4 mode continuously (more on that below). Four-wheel drive systems are better suited for higher towing and hauling loads than AWD vehicles and can handle more slippery and intense terrains than AWD. That’s why most 4WD systems are intended for more adventurous off-road paths, heavier snow conditions or heavy-duty work purposes.

Understanding the basic differences between the two systems is a great start, but to really understand how each one stacks up against the other, we have to look in-depth at how each feature operates and what that means for you as a driver.

All-Wheel Drive Defined

As the name suggests, all-wheel drive means that all wheels on the car are receiving power and rotating independently. AWD is a popular feature offered on many cars, SUVs and crossovers.

Through a system of sensors, the car controls how much torque is being sent to each axle, diverting more power to wheels that need more traction to prevent slippage. This provides extra grip in slippery conditions such as snow, ice and gravel roads, while also boosting control through acceleration in all conditions.

This also means while cornering, the inside tires rotate slower than the outside tires to maintain stability and driver control, which is an appealing feature for certain types of performance drivers.

All-wheel drive systems don’t come in just one form. Different cars and manufacturers have different options. Typically AWD systems can be either part-time or full-time:

• Full-time AWD means that power is constantly delivered to all wheels through a central differential that controls the amount of torque sent to each wheel. The Subaru Symmetrical AWD system and Audi's Quattro are two examples of full-time AWD systems.
• A part-time AWD system, typically found on front-wheel drive vehicles, is designed to only deliver power to the rear wheels when one, or both, front wheels begin to slip. Also called on-demand or real-time AWD, this type of wheel-drive system is automatically activated to achieve the best possible fuel economy while improving handling in slippery conditions. 

With either a full-time or part-time AWD system, the amount of torque delivered to the wheels is automated.

Pros And Cons

The best all-wheel drive vehicles deliver superior performance on wet, icy or muddy roads when compared to front-wheel drive vehicles.

An AWD vehicle is ideal for drivers who travel on gravel roads, or in snowy, rainy or icy conditions. But, AWD cars can also be used on dry roads without compromising safety, which is a concern for 4WD systems.  

While AWD systems can increase driver confidence in snow, heavy rain or icy conditions, even the best all-wheel drive cars, crossovers and trucks still need plenty of stopping distance in poor conditions. Drivers tend to overestimate how much traction their AWD vehicle really has, increasing the risk of skidding while accelerating in icy conditions.

Although part-time AWD systems try to control for this, these cars are still less efficient due to the continuous power being sent to each wheel and the fact that these cars are typically heavier than front- or rear-wheel drive cars.

AWD vehicles will cost more than a two-wheel drive vehicle. The extra cost comes from the complicated drive trains these cars have in order to drive power to all four wheels. In two-wheel drive systems, the drive train is designed to only divert power to either the front or rear tires, making their design and parts simpler than AWD and 4WD systems.

Similar to AWD cars, a four-wheel drive system is designed to send power to all four wheels. The system uses a central differential located between the front and rear axles to lock the two axles together. When the central differential is locked – or engaged – power from the engine is distributed equally between all four wheels, resulting in extra traction and improved stability.

Because the wheels turn at the same speed and the drivetrain is locked, turning is more difficult in 4x4 vehicles when the system is engaged than with AWD systems. In addition, 4WD should never be engaged on dry, paved roads as this could cause drivetrain binding and damage the vehicle.

Since 4WD systems allow for more driver control, there are a few different gears usually offered. Most 4x4 vehicles have three settings: 2H, 4L and 4H.

The 2H setting is designed for everyday use and allows the vehicle to operate similar to a 2WD system, diverting power to just the rear axle and tires. This is ideal for normal driving conditions.

A 4L, or sometimes referred to as a low setting, doubles the amount of torque being applied to all four wheels and restricts the wheel rotation speed. This setting is designed to be used at low speeds and through extreme snow or off-road conditions. This setting should never be used on dry, paved roads or normal conditions.

The high setting, or 4H, is designed for use when extra traction is needed in loose gravel or slippery, icy conditions. Similar to the 2L or low setting, this gear should never be used on dry, paved roads or normal conditions.

Pros And Cons

Four-wheel drive systems are great for extreme conditions as mentioned above or if needing to switch between controls for higher and lower speeds. But, since these systems typically have to be controlled by the driver they require a better knowledge and understanding of how the systems function and when they are needed than AWD systems.

Vehicles equipped with 4WD are ideal for towing boats or trailers because the 4WD system sends power to all four wheels, and that eliminates spinning when starting from a full stop. On older 4WD trucks, drivers needed to manually switch the front wheel hubs to engage the 4WD, whereas late-model 4WD SUVs and trucks have an electronic 4WD switch mounted to the dashboard. 

Unlike front-wheel drive, rear wheel drive or all-wheel drive systems, four-wheel drive systems are designed to only be engaged in slippery conditions, or when hauling heavy loads. These systems really are meant for serious off-roading, deep snow and icy, hilly terrains.

Similar to AWD vehicles, 4x4 systems add additional cost to the price of a car and will impact the overall fuel efficiency of a vehicle. The extra transfer case, prop shaft and differential required by 4WD systems add to the overall purchase price of 4WD vehicles, while the extra weight can lead to a reduction in fuel economy compared to a similar two-wheel drive vehicle.

When deciding between an all-wheel drive vs. 4-wheel drive vehicle, consider your driving habits and conditions where you’ll spend most of your time driving. AWD systems are designed to improve safety and control in slippery conditions such as snow and ice, while providing the added benefit of improved cornering and acceleration at all speeds.

Keep in mind that the main difference between AWD and 4WD is that with an AWD vehicle, the amount of torque delivered to each wheel is automatically adjusted, while on a 4WD vehicle, the driver can select between two-wheel drive and 4WD. This makes 4WD systems ideal for drivers who travel off-road or tow heavy trailers and have an understanding of when and how to use these systems. 

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