The difference between a vehicle with four wheel drive and all wheel drive (AWD vs. 4WD) may not be too important to ordinary citizens, unless you live in a city with snowy conditions or are a fan of driving extremely difficult trails. In this case, it is vitally important to know what one or the other is for and when and how to use them; Here we explain it to you.
The new AWD is the most popular option, but for those hoping to conquer trails, 4WD is vital. However, the drawbacks of the latter can be daunting if you don’t specifically understand what it takes to own a car with this capability. Here’s the difference between four-wheel drive and all-wheel drive.
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Traction on the four wheels (4WD)
Let’s start with “four wheel drive”. Often called 4WD and “Four by Four” (4×4), the main distinction of this system is that it is typically used on vehicles designed and built to be driven off-road. Included here are rugged trucks and SUVs like the Jeep Wrangler, Mercedes-Benz Gelandewagen, and Toyota Land Cruiser.
In short, it is a system that sends power to all four wheels equally and without vectoring (that is, without controlling the division of the power delivery between the wheels or the axles).
Here, each wheel will spin at the same speed as all the others. Power comes from the engine and is transferred to the transmission, where a unique device known as a transfer case splits the power between the front and rear axles.
This equal split of power is great for maneuvering in really tight, low-traction situations. But it is not very friendly in daily driving. When you have a four-wheel drive system to go down the road, it can make simple actions like turning or cornering very difficult.
This is why most 4WD systems are part-time systems, being able to disable two-wheel drive to improve on-road driving.
“part-time” vs. “Full time”
Most modern four-wheel drive systems are “part-time” where the vehicle is in two-wheel drive mode only. A push of a button (or a pull of a center console-mounted lever) activates all-wheel drive.
Basically, it compensates for the differences in the rates of rotation of the four wheels, solving the problems that make handling difficult. Most trucks and SUVs (even all-wheel drive crossovers) come with locking differentials central.
This type of differential sends power evenly to the front and rear axles, but those axles have their own differentials that vary the amount of power between the left and right wheels, depending on the amount of grip available.
That’s when the stability and traction control systems come in to limit actual wheel slip. But this is a discussion for another day…
|4WD Advantages||4WD Disadvantages|
|Better traction in off-road conditions||Adds weight and complexity to cars|
|Can be turned off to improve fuel economy||Cannot be used in all conditions|
|Proven and robust technology||More expensive than two-wheel drive models|
“Full-time” four-wheel drive systems essentially do not have a “2WD” mode, meaning the four-wheel drive system is active all the time.
It’s a somewhat outdated system, as technology and the “part-time system” makes more sense to most consumers these days. Not everyone needs four-wheel drive all the time.
All Wheel Drive or All Wheel Drive (AWD)
All-Wheel Drive is a much more recent innovation and therefore a bit more complicated. It appears in everything from supercars like the Audi R8 to supermarket cars like the Buick Encore. For simplicity, it’s actually very similar to the “part-time” four-wheel drive concept. “”
Four-wheel drive (4WD) is a system that attempts to send as much power to all four wheels as possible for maximum traction. Instead, all-wheel drive (AWD) varies the amount of power sent to each wheel, either physically (via differentials or transfer cases), or electronically (via brake vectoring, where brakes are used). to slow down a specific wheel due to lack of traction).
All-wheel drive is often associated with road vehicles such as sedans, station wagons, crossovers, and even some of today’s larger SUVs. Crossovers like him Honda CR-Vthe Toyota RAV-4 and Mazda CX-3 tend to fall into the “car” category, while SUVs like the Chevrolet Tahoe and Toyota 4Runner fall into the “truck” category.
Think of all-wheel drive as similar to the “part-time” four-wheel drive system just described, except here it’s fully automatic. With all-wheel drive, the system is constantly active and does not need to be activated by the driver to work.
Every time the vehicle systems sense a loss of traction (because of curves, turns, or weather conditions), power is electronically and physically diverted from wheels that need less traction to those that need more. Some constantly send power to both axles and all four wheels, adjusting power delivery according to which wheel loses or maintains traction.
All-wheel drive has also been on the rise in performance applications. The Mercedes-AMG E63 is a perfect example. It is now sold only with AWD in the United States, as its huge power reserves of over 500 horsepower can “overwhelm” rear-wheel drive. Even when we’re not talking about such performance cars, dividing the power evenly means greater all-weather stability.
AWD isn’t as robust as 4WD, and it can’t match the sharp power delivery needed for low-speed off-roading. The maintenance and complexity of these systems can also be extraordinarily expensive, but ensuring their operation is crucial to your safety.
AWD has some clear advantages over 4WD. These days computers are involved in most AWD systems. Sensors on each wheel monitor traction, wheel speed and much more data hundreds of times per second. An ECU (engine control unit) dictates where the power is sent and which individual wheel has more grip.
This type of system, often called torque vectoring, appears in everything from the Subaru WRX to the Dodge Charger. Torque vectoring has enabled huge improvements in handling and the ability of today’s cars to be capable in all types of weather.
Electrified all-wheel drive
Many electric vehicles (such as the Jaguar I-Pace and Audi e-tron) use what is known as an all-wheel drive system.
Each axle has its own electric motor, so all four wheels are always powered, but there is no mechanical connection between the front and rear of the car. This improves traction and performance while helping to clear up passenger space as there is no need for a transmission mound.
Some plug-in hybrid vehicles use a combination of technologies to achieve four-wheel drive. For example the Volvo XC90 T8. Its 2.0-liter four-cylinder engine spins the front wheels, while a rear-mounted electric motor spins the rear wheels.
It has front-wheel drive when all four cylinders work alone, rear-wheel drive works only in electric mode, and all-wheel drive works with both power sources running.
|AWD Advantages||AWD Disadvantages|
|Provides increased grip and control in all road conditions||Reduces fuel economy|
|Gives sportier handling and traction to a wider range of cars||Increases the weight and complexity of vehicles|
|It works all the time||Not so good in extreme off-road conditions|
Automakers are getting serious about electrified cars, so these all-wheel drive systems will become more common in the coming years.
Which one suits me?
Your decision will depend on your needs. If you are a kind of Mad Max who uses his vehicle almost always off-road and in difficult terrain, 4WD will always be the best option. For most people, however, AWD makes more sense.
In wintry conditions, a modern all-wheel drive system will respond instantly without the driver having to flip any switches. It is what most people need. Also, AWD vehicles tend to have better weight distribution, which improves traction and performance.
But the truth is that for many drivers it is not a matter of life or death. If you live in an area that doesn’t have too harsh a winter climate, you’ll probably only notice the difference a couple of times a year, and trust us: in many cases, a good set of winter tires will make the most difference.