AWD vs. 4WD: Know the Differences

Today, preference is shifting once again to AWD and 4WD due to consumer demand for SUVs and CUVs. Despite exhibiting worse fuel economy than FWD cars, AWD and 4WD benefit from greater traction and control, but the two can often be mistaken for one another due to their similarities. 

Modern technologies have made differentiating one another difficult for most, but understanding the difference may mean the difference of getting home after a long trek through Moab or calling in the calvary to save you. 

Don’t fret, as The Drive’s dedicated informational team is here to untangle the wires and explain all the differences between AWD versus 4WD.

AWD and 4WD systems utilize different parts. Here’s a quick breakdown of the related terms, names, and components. 

An all-wheel-drive vehicle typically uses an engine, a torque converter or clutch, a transmission, a center differential, a clutch pack, a rear differential, and a front differential. However, there are numerous types of AWD systems that use unique technologies, like hybrid electric, and equipment.

A four-wheel-drive vehicle uses an engine, a torque converter or clutch, a transmission, a transfer case, a rear differential, and a front differential.

A differential is a mechanical or electronic gear assembly within a drivetrain that splits torque into two output shafts or axles that can operate at different speeds. It can also be locked together. 

For example, a rear differential, which is connected to the rear driveshaft, allows the left and right rear wheels to turn at different speeds. A center differential allows the front and rear driveshafts to operate at different speeds but offers the option to lock the two together. 

There are numerous types of differentials, with the most common being open, locking, or limited-slip.

On AWD and 4WD vehicles, a transfer case is a mechanism within a drivetrain that is connected to a transmission, a front driveshaft, and a rear driveshaft. Typically using gears, hydraulics, or a chain within the transfer case housing, the transfer case will transmit power from the transmission to the driveshafts to power the front and rear axles while allowing the front and rear wheels to move at different speeds.

On 4WD vehicles, the transfer case can be manually actuated by a lever, dial, switch, or button to engage different gear settings. On AWD vehicles, the transfer case automatically works without input.

An all-wheel-drive system delivers power to all four wheels on the vehicle at the same time all the time, but the amount of torque going to each wheel varies. Depending on the system, an all-wheel-drive will normally operate with a front or rear bias. For example, the Subaru Outback defaults to sending 80 percent of its torque to the front and 20 percent to the rear. However, when traction is needed at one or all of the other wheels, the system will funnel power to the axle that is calling for help. 

All-wheel-drive systems use a type of center differential (there are many) that allows for the front and rear wheels to operate at different speeds. In some examples, such as the Ford Edge, the all-wheel-drive system allows for the rear to be completely decoupled to allow for 100 percent front-wheel drive.

Front-Biased All-Wheel Drive: The vehicle skews more torque to the front wheels than the rear wheels.

Rear All-Wheel Drive: The vehicle skews more torque to the rear wheels than the rear wheels.

The purpose of four-wheel drive is to maintain optimal traction when manually selected. A vehicle has four-wheel drive when the front and rear driveshafts can be locked together to move at the same speed and send the same amount of torque to all four wheels. Four-wheel drive is typically intended for use off-road and on extremely slippery surfaces.

A car with part-time 4WD operates in 2WD unless the car is manually or automatically electronically switched to 4WD. One driveshaft is permanently linked to power, while the other can be connected when needed. Part-time 4WD is most often engaged with a button, dial, lever, or switch inside the cabin of the vehicle. This is the most traditional type of 4WD and is often found on 4x4 vehicles such as Jeep-like SUVs and trucks. 

When a vehicle is in true four-wheel drive, it cannot drive normally on regular roads because the front and rear axles aren’t allowed to operate at different speeds. If attempted, the car could start to bind or shudder, a phenomenon known as “crow hop.” This could damage the vehicle.

This is a different type of part-time AWD. A car with on-demand 4WD operates in two-wheel drive by default but automatically calls upon the other wheels when traction is needed.

A car with full-time 4WD, sometimes referred to as permanent 4WD or Auto/Automatic 4WD, equally sends 25 percent of the power to each wheel 100 percent of the time. However, a clutch pack or center differential allows for the front and rear driveshafts to move at different speeds. 

On 4x4 vehicles, there is typically a dial, lever, switch, or set of buttons with various driving configurations. Each option should be used only in the specific intended circumstances, or the driver risks damaging the vehicle. Below, we explain how to use 2H, 4H, and 4L.

2H is an abbreviation for Two High. This means two wheels are engaged, typically the rear wheels, in high range. Drivers should use 2H under normal driving circumstances on hard surfaces.

4H is an abbreviation for Four High. This means four wheels are engaged in a high range gear ratio. Drivers should use 4H when they need extra traction, such as driving on snow or rocky trails, at average speeds of approximately 30-50 mph (check your vehicle’s manual for exact limitations and specifics). 

4L is an abbreviation for Four Low. This means four wheels are engaged in a low range gear ratio. Drivers should use 4L in circumstances when maximum traction and torque is needed, such as in deep sand, mud, or snow. It is also suitable for climbing or descending steep inclines with unstable surfaces. 4L allows for slow controlled speed typically less than 15 mph and greatly helps during off-road crawling.

Electric and hybrid AWD systems operate much differently than AWD systems on traditional gas-powered vehicles. On EVs, there’s no engine, transfer cases do not apply, and mechanical linkages are replaced with computer wires. To operate in AWD, the EV must use electric motors to power both the front and rear axles and all four wheels. Here are a few examples of different types of electric all-wheel-drive setups.

The car features two electric motors. One is located on the front axle and the other is located on the rear axle. Differentials on those axles allow the wheels to spin at different speeds. Teslas call this Dual Motor AWD.

The upcoming electric GMC Hummer is rumored to have three electric motors, likely with one upfront and two on the rear. With two motors at the back, the vehicle could control of each of the rear wheels.

Some electric vehicles use four independent motors built into the two axles or the hubs of each wheel. Once again, computers can control how much power, negative or positive torque, and slippage occurs at each wheel.

Hybrids combine a gas motor with some type of electric assistance. Full hybrids pair gas motors with electric motors. All-wheel-drive hybrids typically use the gas engine to power one axle and an electric motor to power the other to achieve control over all four wheels. In some cases such as the Acura NSX, however, a system will use a gas engine and multiple electric motors. 

This depends on how much snow is present, as well as the purpose and mission of the drive. Driving down a snowy highway? Think AWD. Driving over a snow-covered mud field? Think 4WD. Read more in How to Drive in the Snow. 

Typically, yes, but some modern systems allow the driver to deactivate AWD to use two-wheel drive.

This depends on how the vehicle will be used and the climate it will be driven in.

This is dependent on the buyer’s needs, locale, and budget. The answer is not always yes.

Yes and no, AWD improves traction in slippery conditions, including on ice. But it only helps propel you forward. It won’t help you corner or stop.

Yes, AWD improves traction in slippery conditions, including when it rains.

AWD adds cost, reduces gas mileage, and has complex components that could falter.

Yes, for two reasons: AWD systems require more energy to power more wheels and add weight due to their more complex makeups. 

Technically, yes, but traditionally, no. Select systems allow for the front or rear driveshaft to be fully disconnected. 

With the proliferation of AWD throughout the industry and its manufacturers’ lineups, each company has slightly different technologies and uses slightly different marketing terms to describe the systems in its vehicles. Here are some of the most common systems and what they mean, as described by the manufacturers themselves.

“SH-AWD uses dynamic torque vectoring to provide more accurate and predictable handling performance in all road conditions.

Up to 70% of engine torque can be sent to the rear wheels as needed, with up to 100% of that torque apportioned to either the left or right wheels. Further, today's SH-AWD can overdrive the outside rear wheels by up to 2.7 percent, creating additional rotational speed that helps "pull" the car through the turn with increased grip and cornering accuracy.”

“Fundamentally, Quattro all-wheel drive for Audi medium and large cars works similarly to previous systems with three differentials. It is mechanically as well as electronically activated, and it distributes torque to wheels based on steering angle sensors, traction and stability control, yaw sensors (measuring how weight shifts left or right around its center of gravity) and wheel sensors.

Default power distribution is 40:60 front to rear, with up to 70% of power to the front wheels or up to 85% of a vehicle’s power to the rear. Additionally, electronic wheel-selective torque control can assist traction across each axle through individual wheel braking. Torque control is provided by an intelligent software function of the stability control.

In S and RS models, the rear Sport differential has the ability to overdrive the inside or outside wheel, or even send almost all power from one rear wheel to the other, in hard cornering, creating more neutral handling. This is known as torque vectoring.”

 “With BMW xDrive, intelligent Dynamic Stability Control (DSC) sensors detect the slightest loss of grip, and using an electronically controlled multi-disc clutch, divert the power to the set of wheels that have the best traction, reacting much faster than traditional, hydraulically operated systems. BMW xDrive is a fully variable system that can send almost 100% of the power to either axle, offering instantaneous and effective transfer of engine power.”

“The HTRAC AWD system was developed as a multi-mode system, providing an electronic, variable-torque-split clutch with active torque control between the front and rear axles. The driver-selectable HTRAC Normal, Sport and Smart modes help provide confident control in all weather conditions. The Sport setting gives a more agile feel by sending more available torque to the rear wheels, for a sporty dynamic feel when desired.”

“Available active on-demand all-wheel drive helps provide enhanced driving performance by actively distributing torque between the front and rear wheels depending on road conditions and driver input. The system utilizes electro-hydraulic AWD coupling to precisely activate the multi-plate clutch plate, constantly redistributing the amount of power transferred to the front and rear wheels. 

During normal driving, power is distributed according to the drive mode selected. Eco and Smart modes deliver 100 percent power to the front wheels. Comfort and Snow modes deliver 80 percent power to the front wheels and 20 percent to rear. Sport mode splits the power 65-35 percent between front and back. Lock mode delivers power evenly to all four wheels.”

“Mazda’s advanced i-ACTIV AWD system uses sophisticated real-time vehicle dynamics modeling to help predict the available grip at each tire and sends torque to the wheels that can use it best. The system comes into play before the front wheels lose grip, engaging the rear wheels to deliver traction where and when it counts.”

“At its core, the 4MATIC system feeds power to the front axles through a transfer case in the transmission, while a limited-slip differential provides a balance between front and rear. Sensors manage the torque demands of each wheel, resulting in greater traction and acceleration.” 

“The compact and weight-optimized all-wheel-drive consists of a power take-off on the front axle transmission, a two-section propeller shaft, and rear axle transmission with an electro-hydraulically regulated hang-on clutch. The intelligent controller of the ALL4 system is interconnected with the Dynamic Stability Control (DSC) and constantly calculates the ideal power distribution ratio between the front and rear wheels. This means that the outstanding engine power is always channeled to the place where it can be most effectively and efficiently translated into driving fun.

In normal driving conditions with the DSC activated, it transmits the drive torque in a brand-typical manner to the front wheels. But if the DSC controller detects a danger of slip on the front wheels, the hang-on clutch will transfer the drive torque to the rear wheels with the aid of an electrohydraulic pump.”

“The new lightweight S-AWC electronically distributes driving torque between the front and rear wheels, along with Active Yaw Control (AYC). The new system offers enhanced tracking performance through cornering, and improves vehicle stability and steering response through the use of a yaw control sensor that precisely controls vehicle yaw rate by applying brake pressure on an inside wheel to pull the vehicle back into line for improved vehicle stability and dynamic composure.

Additionally, a driver-selectable push-button allows drivers to select from four distinct driving modes – the standard Normal mode, enhanced feel in slippery conditions with the Snow setting, maximum control in Lock, and an AWC Eco mode that maximizes fuel efficiency by prioritizing drive to the front wheels and still switches in a split-second to all-wheel drive when multiple sensors determine its necessity.”

“The principle philosophy for any Porsche with active PTM is the same: Enhanced driving dynamics, improved driving safety, and increased traction for an even sportier driving experience. It distributes drive torque between the front and rear axles actively and very quickly. 

Permanent monitoring of driving status means PTM can be actively pre-set to respond to different driving situations: For example, sensors continuously monitor the speeds of all four wheels, the longitudinal and lateral acceleration of the vehicle, as well as the steering angle. By evaluating all sensor data, it is possible to adjust the distribution of propulsion force to the front axle as quickly and effectively as possible.”

“The Subaru Symmetrical AWD system is designed to optimize both traction and balance. The entire system lies along the centerline of the vehicle, balancing weight distribution between the two sides to help provide optimal performance and control. The system sends power to all wheels simultaneously for maximum traction and acceleration. In slippery conditions, that power is actively distributed to the wheels with the best traction.”

“The Camry and Avalon AWD system can direct up to 50 percent of engine torque to the rear wheels, in response to acceleration from a start or slippage at the front wheels. Notably, when AWD isn’t needed, such as on long highway stretches, the electromagnetically controlled coupling on the front of the rear-drive axle can disengage the propeller shaft from the differential to prioritize fuel efficiency. The AWD is designed to re-engage in an instant when needed.”

 “On all MQB (modular transverse toolkit) models with the 4MOTION all-wheel drive system, power is distributed between front and rear axles on an infinitely variable basis by a multi-plate clutch. Normally, power is mainly transmitted to the front axle, which saves energy. However, in the event of an impending loss of traction, the rear axle is activated in a fraction of a second. This is why 4MOTION is considered to be a permanently engaged four-wheel-drive system. 

The distribution of power to all four wheels becomes active before wheelspin occurs. A loss of traction is therefore virtually excluded. There is no fixed distribution of power. Power distribution is continuously adjusted to actual driving conditions. However, should any wheel slip, power is immediately transmitted to the wheels where it is needed.”

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