The automotive industry is quite adept at jargon-ry and there’s no better example of this tendency than the AWD vs 4WD confusion. You’d often find people casually mixing the two up when making a point. Of course, it doesn’t help that the underlying principle of both AWD and 4WD is that they drive all four wheels of a car. And it also definitely doesn’t help that both technologies have matured a lot in recent years, thus mitigating a lot of their traditional shortcomings.
However, that’s where the similarity ends and makes way for the difference between AWD and 4WD, which continues to be significant enough to influence your buying decision. So, without further ado, let’s understand all-wheel drive and 4-wheel drive, and their respective advantages and disadvantages.
What is All-Wheel Drive and how does it work?
An all-wheel drive system powers all four wheels of your car. Within AWD systems, you have either full-time AWD or part-time AWD. In full-time AWD, both the front and the rear wheels are powered, all the time. But in part-time AWD, either the front or the rear wheels are powered, all the time. Bear in mind that in both types of AWD, the driver has no control over the amount of power a wheel (or set of wheels) receives.
Instead, this decision is outsourced to a computer that relies on a string of sensors to gauge the traction status of each wheel’s tyre. If it senses a certain wheel (or set of wheels) needs more power than what’s available, the system sends additional torque right away.
A good real-world example to understand this is when you’re taking a corner at high speed, which causes a greater force to bear down upon your car’s outer wheels compared to the inner wheels. Consequently, the outer wheels require more power as their tyres have greater traction (as in, road contact) than the inner wheels, a requirement that an AWD system fulfils.
By taking the decision out of the driver’s hands, an AWD system can maximise your car’s traction across different driving conditions. The latter is particularly important in regions that see extreme weather as the AWD can modulate the power delivered to each wheel (or set of wheels) as per the traction status of the four wheels at any given moment. An AWD does all this magic via several differentials, hydraulic couplers and/or multi-plate clutches, which are controlled by the aforementioned computer.
What is 4-Wheel Drive and how does it work?
A 4-wheel drive powers all four wheels of your car, equally divided between the front and rear wheels. Within 4WD systems, you have either full-time 4WD or part-time 4WD. In full-time 4WD, all four wheels are powered at all times since there is no 2WD mode on the system. In part-time 4WD, it’s generally the rear wheels (so, a 2WD) that are powered continuously with power sent to the front wheels only when required. This is where a 4WD differs from an AWD as the decision to send power to a set of wheels is made by the driver (through a button or a lever) instead of a computer.
Additionally, a 4WD system usually gets two modes – low-range and high-range. While the former is useful to maximise traction in low-speed, intense off-road situations, the latter improves traction in less intense off-roading and slippery driving conditions (such as loose sand, gravel, and snow/ice).
Depending upon the car, a 4WD does all this through a mechanism of couplings, transfer cases, and differentials at the front, centre, and rear. In fact, certain advanced 4WD cars also offer selectable modes and locking differentials, which enable the driver to control how much power is allocated between the front and rear wheels.
To understand how a 4WD functions, consider a car navigating severely broken and unpredictable roads, puddles, slush, or rocky terrain. In each case, there’s a good chance of one or more wheels losing traction, partially or fully. When this happens, the driver can engage the 4WD system to power the wheels that still have traction and get the car to safety. This ‘on-demand’ aspect of 4WD makes it better than an AWD system for serious off-roading as the latter is more reactive in its response, which would mean a significant loss of traction before the AWD kicks in. With a 4WD, the driver can adopt a more proactive approach and engage the system at will.
What are the advantages and disadvantages of All-Wheel Drive (AWD)?
Advantages of all-wheel drive include:
- An AWD system is completely automated, i.e. the driver is freed from having to decide which wheels get additional power. The AWD system powers all four wheels and can modulate that power to each wheel to ensure optimum traction is available at all times.
- Building on the first point, AWD vehicles offer excellent handling as the torque supply can be varied for each wheel. This is also why a lot of sports cars come with AWD.
- AWD cars can tackle a wide variety of surfaces with relative comfort and ease, including wet/slushy, snowy roads and light off-roading scenarios.
- AWD cars are available in a variety of body styles, including crossovers, sedans, and SUVs.
Disadvantages of all-wheel drive include:
- An AWD system is a complex web of mechanical and electronic parts, which increases a car’s cost considerably.
- Although it can tackle a variety of surfaces with ease, an AWD system is not suited for intense off-roading as the driver has no control over it.
- As all four wheels are driven all the time, an AWD car offers lower fuel efficiency.
What are the advantages and disadvantages of 4-Wheel Drive(4WD)?
Advantages of 4-wheel drive:
- A 4WD system is based on manual control, i.e. the driver decides when to engage 4WD through a button or lever.
- A 4WD system is very robust and enables a car to tackle intense off-road conditions with ease. A 4WD vehicle is also equally at home on broken roads. This is why a lot of full-blown SUVs offer a 4WD option or have it by default.
- Contrary to popular perception, modern 4WD systems are quite refined and offer a car-like driving experience.
Disadvantages of 4-wheel drive:
- Compared to 2WD cars, a 4WD car delivers a stiffer ride quality, which can affect passenger comfort.
- A 4WD system increases a car’s initial cost while also incurring higher maintenance expenses in the long run.
- When engaged, a 4WD system hampers fuel efficiency.
Difference between All-Wheel Drive Vs 4-Wheel Drive
4WD vs AWD differences include,
- In AWD, a computer decides how much power a wheel gets, based on its traction status. In 4WD, the driver decides when all wheels get power, based on driving conditions.
- In AWD, the power sent to each wheel can be different, based on traction requirements. In 4WD, the same amount of power is sent to each set of wheels. However, some 4WD systems allow power to be split between the front and rear wheels in unequal ratios, e.g. a 60/40 4WD system means 60% of the power goes to the front wheels and 40% of the power goes to the rear wheels.
- In terms of handling and road grip, AWD cars are better than 4WD cars as torque to each wheel can be modulated as required. This makes AWD cars more suited to slippery and unpredictable road conditions than 4WD cars.
- In terms of off-roading ability, 4WD cars are better than AWD cars as they’re more rugged and allow the driver to engage the system when dealing with low-traction conditions. This makes 4WD cars a better option for surfaces such as broken roads or no roads.
- Both AWD and 4WD consume more fuel than a conventional 2WD vehicle. However, AWD cars are more fuel efficient than 4WD ones as they send power to a wheel only to the extent required, falling back to 2WD in normal conditions. Conversely, when engaged, a 4WD consumes more fuel than an AWD as a fixed amount of power is sent to all wheels. Also, AWDs are more optimised for efficiency than 4WDs.
All-Wheel Drive Vs 4-Wheel Drive: Summary
The difference between AWD and 4WD is narrower than ever before thanks to technological advancements. For instance, the bouncy and stiffer ride associated with 4WD cars has been mitigated quite a bit with improvements in chassis rigidity and suspension tech. Similarly, the off-roading ability of AWD cars is constantly improving with advanced sensors helping a car retain traction across most surface conditions.
However, there are still areas where one does better than the other. For example, for highly broken surfaces or heavy off-roading, a 4WD is still a better bet, especially with the additional ground clearance and manual control at your disposal. But for an everyday car that can tackle all kinds of road conditions with some light off-roading thrown in, an AWD car is the better option, especially as it offers better ride quality and handling than a 4WD car.
FAQs on All-Wheel Drive Vs 4-Wheel Drive
What is the difference between 4WD and AWD?
An AWD drives all wheels all the time while a 4WD usually drives only the rear wheels all the time, allowing the driver to choose when to send power to the front wheels. An AWD system is also completely automatic while the driver controls a 4WD system.
What is the benefit of all-wheel drive?
An all-wheel drive system can control the amount of power delivered to each wheel, thus maximising the car’s traction in all road conditions. This translates to better ride quality, handling, and overall smoothness while driving an all-wheel drive car.
Which is better, 4WD or AWD?
A 4WD is better on broken or non-existed roads and for extreme off-roading. An AWD is better for everyday usage as it can keep the car composed in slippery, slushy, wet, snowy, and icy road conditions. In terms of ride quality and handling, an AWD is better than a 4WD. In terms of ruggedness, a 4WD is better than an AWD.
Can AWD go off-road?
An AWD can go off-road, but only up to a limit as the driver can’t control the power that’s sent to each wheel. As all the wheels are powered all the time, this restricts the ability of an AWD car to tackle very bad roads and surfaces.
Is all-wheel drive good in rain?
An all-wheel drive is very good in the rain as it modulates power sent to each wheel as per the traction status of each wheel. This increases the car’s overall traction and makes it more stable and controllable. The same benefit applies in other slipper conditions such as snowy, icy, and sandy roads.
Is AWD as good as 4WD in the snow?
For the most part, an AWD and 4WD perform equally well in snow. However, a 4WD is better than an AWD when it comes to tackling deeper snow and severe winter conditions.
