How Does 4WD Outperform All Wheel Drive
Ever wondered about the superiority of the 4WD over the AWD? While both can enhance traction compared to traditional front- or rear-wheel drive, the 4WD reigns supreme.
Read on as we dive deeper into the details of each system and what makes 4WD more capable than AWD.
AWD and 4WD Explained
All-wheel drive (AWD) generally refers to a full-time 4WD setup that lacks differential locks or low secondary gearing in the transfer case/center differential.
Meanwhile, 4WD can refer to either a part-time 4WD system with a simple transfer case
or a full-time 4WD system with a selectable locker in the center differential.
AWD supplies power to the front and rear differential, enabling the front and rear driveshaft to rotate at different speeds (thanks to features like the center differential and viscous coupling).
AWD systems may include open, limited slip, or locker-style differentials at the front and rear, depending on the manufacturer.
So, AWD systems are generally lighter than 4WD systems, although there are exceptions. Some AWD systems are 4WD setups that only include a single-speed transfer case and a viscous coupling.
These features enable AWD systems to be used safely on regular roads without risking damage to the system. Since turning requires the inner and outer wheels to rotate at different speeds, as well as the front and rear wheels, AWD’s differential features make it ideal for regular road use.
On the other hand, 4WD is usually a heavy and robust system that locks the front and rear driveshafts to turn together. Front and rear differentials are equipped with limited-slip or locker units (although locker units were more common in the past, “4WD” is now used more loosely).
Why Is 4wd Better for Off-Road Than All-Wheel
4WD tends to have a leg up on AWD when it comes to off-roading- and for a good reason.
Better for Serious Off-Roading
While AWD is great for regular street driving in tricky weather conditions, 4WD is the way for serious off-roading. This is because 4WD often comes with locking differentials. In contrast, AWD typically uses a combination of technologies that don’t include locking diffs due to driveline binding and compatibility issues with ABS and traction control systems.
More Control Over Power Distribution
AWD systems are generally less robust and more likely to break down when faced with tougher off-road conditions. They offer less control over power distribution to each wheel because the computer handles this rather than the driver.
With 4WD, the driver has more control over power distribution, especially switching between 2WD and 4WD. AWD systems can struggle with power distribution, as they may try to send all power to just one or two wheels when more traction is needed, whereas 4WD with locking differentials offers the extra traction required to overcome obstacles.
Capacity to Handle Tougher Conditions
While AWD is great for mild off-road conditions such as snowy pavement or maintained forest roads, it must catch up when handling tougher terrain due to limited wheel travel, clearance, and load capacity in the drivetrain.
AWD systems rely heavily on electronics for management, which can quickly become overwhelmed in challenging situations. 4WD systems have more capacity to handle tougher conditions without drama.
Fuel-Efficient & Low-Range Transfer Case
Another key difference between AWD and 4WD is that 4WD lets you select between 2WD and 4WD and usually has a low-range transfer case. AWD is always in 4WD mode, and some models may not have a hi/low selectable transfer case.
AWD is also less fuel-efficient than 4WD, as you can’t switch to 2WD when driving around town. Locking differentials is the only way to get 100% power to all four wheels in both AWD and 4WD vehicles.
Essentially, 4WD locks all wheels together, ensuring they turn at the same speed. This is perfect for off-road driving or in poor traction environments, as it provides optimal driving force.
However, 4WD should never be used on-road, as without differential action, the system binds up when attempting to turn and can break.
Additionally, 4WD can have issues in snow, as all wheels turning together can cause it to move forward in a straight line (although this is not always the case, and experienced drivers can compensate for it).
NB: It’s important to note that hardware variations between AWD and 4WD can’t be compensated for with computer management of ABS modulation or torque distribution.
While an AWD system with separately controllable electric motors could come close to the capabilities of a 4WD system with locking differentials, ICE-driven AWD systems are limited in their ability to overdrive some wheels continuously.
Even with four motors driving every wheel separately, in a cross-up situation, the power delivered to each wheel is still limited or restricted to 25% of total power compared to a 4WD with lockers that can deliver 100% of power to any single wheel.
When is AWD Better?
Despite all the shortcomings in off-roading, All-wheel drive vehicles offer superior handling and confidence on slippery roads, thanks to their ability to shift power to the wheels that need it most.
A computer system continuously monitors traction on each wheel, making adjustments on the fly to help drivers stay on the road.
But while AWD can be helpful in certain off-road situations, there are better options for extreme terrains- as earlier mentioned. Constant power shifting between wheels can be less effective in these conditions, and a 4WD setup is generally more durable and robust.
Nonetheless, AWD can provide a significant advantage for everyday driving and enhance your driving experience.
What are the downsides of using AWD or 4WD vehicles for Off-Roading?
Despite providing better traction, neither system helps a vehicle come to a stop, which can lead to overconfidence and accidents.
Additionally, equipping a vehicle with AWD or 4WD generally results in a fuel economy penalty due to the extra weight and mechanical resistance required to turn all four wheels.
This can also make complicated drive trains more expensive, with some upgrades driving a new vehicle up by thousands of dollars.
Furthermore, tires are a crucial factor to consider when driving in harsh conditions. AWD or 4WD vehicles may only be effective if their tires are worn or corrected.
In some cases, a front-wheel drive vehicle with good snow tires may outperform an AWD vehicle outfitted with all-season tires. Ensure that tires affect traction before venturing into the snow or off-roading.
The Difference between 4WD And AWD
The distinction between 4WD and AWD is often blurred, causing confusion and misinformation among car enthusiasts. Though both systems distribute engine power to all four wheels, the way they do so differs significantly.
4WD vehicles utilize a Transfer Case, which splits power evenly between the front and rear axles. At the same time, AWD cars employ a Differential or Transaxle to determine how much power is allocated to each wheel.
Despite its lack of sophistication, the Transfer Case is preferred for off-road driving because it ensures power is evenly distributed between axles, providing better traction on challenging terrain.
However, driving a 4WD vehicle with the Transfer Case engaged full-time is not recommended due to the system’s inability to accommodate different wheel speeds between the front and rear.
In contrast, AWD systems employ mechanical and/or computer-controlled electronics to regulate power distribution among the wheels, allowing them to be full-time.
Marketers may attempt to misrepresent AWD as 4WD by adding off-road features. So beware of their deception. Ultimately, the effectiveness of an AWD system is heavily influenced by the type and programming of the differential. So let’s explore the fascinating world of differentials!
Three types of differentials allow a vehicle’s wheels to rotate at different speeds:
The first type, an open differential, sends power along the path of least resistance. This means that if one wheel is on a slippery surface and the other is on dry ground, all the power will be sent to the wheel on the slippery surface, rendering the differential useless.
Some modern cars try to trick open differentials into acting like limited slip differentials by using ABS braking systems to maintain the parameters of the wheels.
Limited-Slip Differential (LSD)
The second type of differential is called a limited-slip differential (LSD), which allows some speed differential between the front and rear axles to ensure a smooth ride.
However, it will engage front and rear axles at a certain threshold. Several sub-classifications of LSDs, such as Torsen, viscous couplings, and Haldex, govern slippage and power distribution.
Locked (Full-time) Differential
Finally, we have the locked differential, also known as a “full-time” or selectively lockable differential, which mimics a traditional transfer case by either always or selectively routing torque to the front and rear axles. It’s a binary system that is either on or off, depending on the operator’s discretion.
One of the biggest misconceptions about 4WD and AWD systems is how they control traction from side to side of the vehicle. However, the truth is that neither system has any bearing on power distribution to the left or right wheels.
In fact, regardless of the type of vehicle – AWD, 4WD, FWD, or even RWD – front and rear axles are equipped with differentials to manage torque distribution.
These differentials come in various forms, including open, limited slip, and locking, and control torque from side-to-side rather than front-to-rear as a center differential does.
Moreover, technological advancements have led to new approaches to all-wheel traction that use electric motors to drive one set of wheels while the combustion engine drives the other.
This allows for FWD-only electric cruising or all-wheel full-power blasts. In all cases, onboard computers must govern fore and aft torque distribution. Ultimately, the type of vehicle, tire, and differential type impact traction and performance more than AWD or 4WD systems.
So, whether you’re conquering off-road terrain or navigating snowy roads, focus on the mechanicals, not marketing gimmicks, and make the most of your driving experience.
Mechanical Differences Between AWD, RWD, and 4WD
Do AWD, 4WD, and RWD have any significant mechanical distinctions, or are they flashy buzzwords used to sell cars? To answer this question, let’s examine gasoline or diesel engine vehicles with two axles and two wheels each- like an average truck or SUV.
The engine’s rotary motion is transferred to the drive wheels via a “powertrain” system in these vehicles. This system consists of a gearbox, transfer case, and axle gearbox.
The front-wheel drive (FWD) system is driven solely by the front axle. The rear-wheel drive (RWD) system is driven only by the rear axle. However, things need to be clarified in the AWD or 4WD systems.
While there is no universal definition for AWD or 4WD, both systems can drive the front and rear axles- with one axle as the primary driven axle and the other as the secondary.
The secondary axle can be engaged all the time. Or only as needed, manually or via an automated system that factors in various driving considerations, including safety, stability, acceleration, and fuel economy.
AWD systems are typically derived from FWD powertrains and always engage both axles, modulating torque as necessary for optimal performance. AWD is often associated with cars and vans.
On the other hand, 4WD systems are derived from RWD powertrains and require manual engagement of the secondary axle. 4WD is commonly found in trucks and SUVs but should not be used on dry pavements due to poor fuel economy and potential wheel fights.
Historically, 4WD became popular during World War II for its ability to traverse difficult terrains. The original “Jeep” type of drivetrain featured a transfer case to drive the rear axle continuously and transfer drive to the front axle as needed for better traction.
However, this setup resulted in poor fuel economy and drivability issues on paved roads.
Modern AWD systems have evolved from the original Jeep transfer case setup, with center differentials connecting the drive to the rear and front axles to prevent them from fighting on the dry roadway.
Also, slip-control clutching devices have improved efficacy by conquering torque limits on the wheel with the least traction.
Overall, while there are mechanical distinctions between AWD, RWD, and 4WD, they are often nuanced and context-specific. It’s important to consider your driving needs and preferences when selecting a drivetrain rather than relying solely on marketing terms.
This video has been included for its clarification of the topic matter. Credit goes to
The Final Verdict: 4WD Reigns Supreme
After a thorough comparison, it’s clear that 4WD is the ultimate choice for off-roading purposes. Despite being heavier and pricier than AWD, its capabilities make it a justified investment.
AWD is more suited for daily drivers, assisting them in maneuvering on poorly-tractioned, man-made roads. However, rugged off-road escapades are best tackled by robust 4WD vehicles.
4WD is the elder sibling of the two systems, dating back to locomotives and the first automobiles during the industrial revolution. Nowadays, you’ll likely catch glimpses of 4WD vehicles powering through challenging off-road terrains in car commercials.
4WD is engineered to distribute torque to all four wheels, amplifying the vehicle’s power and traction. More advanced 4WD systems can be operated full-time, while most 4WD cars have a part-time system that drivers can engage or disengage.
The system secures the front axle to the drivetrain when activated, causing all four wheels to rotate in unison.
Additionally, 4WD has higher and lower gear sets called 4-high and 4-low, respectively, designed for specific environments. 4-high functions best on even terrains like roads with fresh rainfall, ice, or snowfall, allowing the vehicle to reach speeds of 55 mph in less-than-ideal conditions. Conversely, 4-low is intended for shallow streams and increases the car’s towing capacity.
Car manufacturers typically pair 4WD systems with heavy-duty suspensions and other unique modifications- further enhancing the vehicle’s off-road performance. Because of these factors, 4WD is the go-to choice for most seasoned off-roaders. However, the system still has some drawbacks.