Diff between all wheel drive and 4 wheel drive

All wheel drive or AWD means that the vehicle is designed to provide power to all four wheels at the same time, and in most cases cannot be switched to the two wheel drive (2WD) option. The distribution of power to the front- and hind-set of wheels differs from one system to another.

4WD or four wheel drive (part time and full time) also means the vehicle has a drivetrain that allows all four wheels to receive torque from the engine simultaneously. AWD and full time 4WD essentially mean the same thing except for some difference in the power settings — 4WD has three settings: 2WD (two wheel drive), low and high; while most AWD vehicles lack the 2WD option. These terms are interchangeably by car manufacturers, so you should ask for detailed information about the vehicle, before investing in one.

For vehicles with more than 4 wheels, AWD implies that all the wheels are powered, and 4WD means that four wheels are being powered.

Comparison chart

Pros and Cons of AWD and 4WD

AWD systems and full time 4WD systems have a central differential that allows it to run on any road conditions and is designed for all season use. However, it consumes more fuel and is more expensive than other systems. Part time 4WD systems, however, have to be engaged from a two wheel to four wheel mode when needed and disengaged when not required to avoid mechanical damage. This can be cumbersome if one is used to travelling in rough conditions. This system is ideal for people who do not want to buy an expensive 4WD and still want the option for occasional use.

Types of AWD and 4WD

AWD can be automatic or selectable AWDs. Automatic AWD, as the name suggests is an on-demand system, which means that in normal road conditions only one axle of the vehicle is engaged. In rough road conditions, the second axle becomes engaged. In selectable AWDs, you can choose between degrees of wheel engagement. This type of system in seen in cars or crossover SUVs.

4WDs can be part time or full time 4WDs. Part time 4WDs are designed so that the settings can change from 2WD to low or high 4WD manually using a lever or switch. 2WD condition is used to drive on normal road conditions. Low 4WD settings are use to drive on very slippery roads, sand, steep areas or mud where the speed of the car is very low (generally below 25mph). High settings are used when driving on snow, ice, rocky roads when you can drive at higher speeds.

The 4WD feature, however, has to remain disengaged while driving on a dry pavement. The change in the settings can be done while driving only in the newer models. In older models, the car has to come to a complete halt before changing it to the low setting to avoid mechanical damage. This type of system is advantageous for people who do not intend to use 4WD all the time and only want it for safety on a slippery road.

Fulltime 4WD can remain engaged all the time, even when driving on a dry pavement although there is an option to switch from high to low setting which has to be done when the car is at a halt. This system is generally seen in trucks or heavy SUVs.

Examples

Some examples of vehicles with AWD are Pontiac Vibe, Toyota Matrix, Ford Fusion etc. Examples of part time 4Wd are Suzuki SUVs, and fulltime 4WD are Toyota Sequoia, Mitsubishi Montero etc.

The difference between all-wheel-drive (AWD) and four-wheel-drive (4WD) is a topic of confusion for many car, truck, and SUV buyers. Both systems send power to the wheels where traction is needed most. But if you find yourself wondering which is better, AWD or 4WD, these guidelines will help:

• AWD is a good fit for everyday all-weather conditions, light off-roading, and certain kinds of performance driving
• 4WD is the better choice for taking on heavier workloads and traveling over challenging terrain 

Photo: Christian Wardlaw

For these reasons, we usually associate AWD with cars and crossovers and 4WD with SUVs and pickup trucks. However, the lines of distinction between AWD vs. 4WD remain blurry for many. Therefore, a car buyer should understand the operational differences between the two systems before deciding which one is right for them.

AWD systems typically operate without any driver involvement. They are computer-controlled systems that use sensors to automatically decide which axle and which wheels receive the most power at any given moment when road surface conditions or vehicle dynamics demand extra traction. The wheels receive varying amounts of torque through a system of differentials and clutch packs, which distribute power to optimize traction in rain, mud, snow, and ice.

In everyday dry pavement driving, AWD can elevate steering precision, particularly in turns. For this reason, many high-performance applications integrate AWD along with torque vectoring capabilities to boost cornering prowess at higher speeds. An excellent example of this is Acura's Super Handling All-Wheel Drive (SH-AWD – pictured in the transparency image), the latest version of which is available in the redesigned 2022 MDX SUV.

There are two kinds of all-wheel-drive systems: full-time and part-time. Full-time AWD continuously motivates all four wheels. Part-time AWD usually remains in front-wheel-drive (FWD) or rear-wheel drive (RWD) mode until more traction becomes necessary. At that point, the part-time AWD system directs power to the axle and wheel(s) in need. Some AWD systems offer a locking differential that equally splits power between the front and rear axles for maximum traction at low speeds.

An AWD system's most apparent advantage is that the driver is not required to do anything to engage the system. Either all wheels are receiving full-time power, or the system is automatically allocating torque to maintain traction. And because this is a computer-based system, the real-time decisions it makes will be better than a human can make.

A disadvantage is that AWD cannot take on extreme off-roading or rock crawling. For those who seek serious adventures, AWD will likely not suffice.

Another disadvantage of AWD is related to fuel efficiency. Compared to a two-wheel-drive (2WD) setup, AWD vehicles generally have lower fuel economy ratings. This is especially true of the full-time systems, which power all four wheels at all times.

Like AWD systems, 4WD can send torque to all four wheels to maximize traction when needed. Unlike AWD systems that activate automatically, the driver typically must engage 4WD with the push of a button or a pull of a lever. However, some 4WD systems, such as the Autotrac system available in vehicles such as the Chevrolet Tahoe and GMC Yukon, offer automatic 4WD operation.

Traditional 4WD systems are also more robust than AWD setups and can handle higher towing and hauling loads as well as rugged terrain. That is why they are more commonly available on traditional SUVs and pickup trucks intended for heavy-duty work and more challenging environments requiring higher ground clearance.

Mechanically, 4WD systems use a front, center, and rear differential and a two-speed transfer case to send all four wheels power. The driver can decide to keep power flowing to the rear axle or direct some percentage of the torque to the front wheels. The transfer case also allows the driver to select between 4-Hi or 4-Lo gearing. The 4-Hi setting is appropriate for wet or icy road conditions similar to a typical AWD system, while the 4-Lo setting provides maximum traction in difficult off-road situations.

Some 4WD systems are full-time, sending power to all four wheels continuously. Some, like General Motors’ Autotrac, automatically engage 4WD when necessary, similar to an AWD system. But most 4WD systems feature part-time operation. Unless the driver actively selects 4-Hi or 4-Lo when road conditions or driving circumstances call for it, the vehicle is only using two of its four wheels to propel itself. With some systems, the driver can also lock the differentials for extra traction in difficult off-road situations.

Vehicles with 4WD inspire confidence in even the most adverse driving conditions. They are also ideal for travel over treacherous terrain or providing the pulling power needed to tow trailers, boats, and machinery. Overall, 4WD vehicles are well-suited for heavy-duty work and play.

As 4WD systems become more sophisticated, new technologies are emerging to aid in serious off-roading. One example is off-road cruise control, available in the Ford F-Series truck and the trail-ready Jeep Gladiator and Wrangler models. When the transfer case is in low range, off-road cruise control enables the vehicle to maintain a set speed under five miles per hour during off-roading and rock crawling. This technology allows a driver to concentrate on getting around, over, or through whatever obstacles present themselves.

Disadvantages of 4WD include the heavy-duty suspensions that often accompany them, making the truck's or SUV's ride quality harsh and unforgiving. Also, 4WD can yield low fuel economy due to the extra power needed to drive all four wheels and the additional weight of the system's components.

If you're trying to decide whether you need a vehicle with AWD or 4WD, the answer is simple. It depends on the kinds of driving conditions you experience regularly and what you plan to do with your car, truck, or SUV. 

An AWD car or crossover may work best for those who need increased traction during typical winter weather, possibly intend to do some light off-roading, and enjoy taking roads less traveled at engaging rates of speed. For those who need a more rugged vehicle that allows the driver to actively control the power flow to the wheels, 4WD is most likely the right choice.