What is the difference between 4WD and AWD?
The short answer
In general, all-wheel drive (AWD) systems are run automatically by the car, are normally always engaged, and are best suited for on-road use in areas with variable weather. Four-wheel drive (4WD) systems are normally a part-time setting that is turned on manually by the driver and are best suited for slow, technical off-road driving.
The long answer
Four-wheel drive (4WD) and all-wheel drive (AWD) seem like they could be interchangeable, right? Personally, I've never seen a five-wheel car before (though apparently a five-wheel car once existed in the 1950s to assist with parking).
But 4WD and AWD are distinctly different both in terms of how they function and the types of driving conditions they are best suited to handle.
A quick note for the car nerds: In my research I found that there are many different sub-types, settings, and complexities with 4WD and AWD systems. My breakdown is meant to provide broad strokes on the systems for the average person to get the gist of things.
What is 4WD?
Four-wheel drive (or 4x4 or 4WD) is a system on a car where the engine powers both the front and rear axles when engaged. Most commonly, 4WD is a part-time setting that the driver can toggle on or off with a button or switch depending on the situation.
When 4WD is engaged, the front and rear axles are connected, allowing power to be transmitted to both. That means better traction. If one or two wheels start to lose grip, the other wheels propel the car forward.
When 4WD is engaged, all four wheels are powered. This is handy when one wheel loses traction, as the other wheels will continue to propel the car forward.
Left: Diagram of all four wheels powered in 4WD mode on a gravel road. Right: Diagram of all four wheels powered in 4WD mode on a gravel road, even when rear left wheel loses traction in a puddle.
Note: This is an oversimplified graphic and the amount of power may vary depending on the type of 4WD engaged.
Note that this doesn't necessarily mean that all four wheels spin at the same speed. 4WD cars still have differentials which allow the left and right (and sometimes front and rear) tires to spin at different speeds to allow for smoother turning. But some cars will have a locking function so that the driver can choose to lock the differentials, ensuring that the wheels spin at the same speed, and providing the most traction to get out of a sticky situation.
Cars should not be driven with the 4WD setting on at all times because it can cause stress on the vehicle components during turns.
Here are some reasons why you might choose a 4WD car:
You like to do off-roading on rough, unpaved roads, through mud, over rocks, or on rugged trails.
You live in an area where you need to drive through deep snow and ice.
You want more traction while going up or down steep hills, especially if the surface is loose or slippery (like gravel or wet grass).
You need to tow heavy trailers or haul loads, especially on an incline.
What is AWD?
All-wheel drive (or AWD) is a system in a car where power can be distributed to each wheel independently, based on the traction needs detected by the vehicle's sensors. Unlike with 4WD, AWD is typically active all the time, managed automatically by the vehicle's computer system.
In an AWD vehicle, sensors constantly monitor each wheel's speed, the vehicle's motion, and the amount of grip or slippage occurring at each tire.
During normal driving conditions with good traction, many AWD systems will predominantly power the front or rear wheels. However, upon detecting wheel slip, the system can quickly redirect torque to the other axle, ensuring that power is sent to the wheels with the most grip. This is particularly advantageous on roads with varying conditions, like patches of ice or wet spots, where sudden changes in traction can occur.
In an AWD car, most of the power is usually delivered to the front or rear wheels during normal road conditions. However, if a wheel starts losing traction, the sensors automatically redirect power to other wheels for stability.
Left: Diagram of an AWD car delivering the front wheels power during normal driving conditions. Right: Diagram of AWD car adjusting power to other wheels when front left wheel starts to lose traction with a puddle.
Note: This is an oversimplified graphic. Some AWD systems may deliver some amount of power to all wheels during good conditions. The amount of power delivered to the wheel going over the puddle may vary depending on the car.
Here are some reasons why you might choose an AWD car:
You're mostly doing everyday driving on paved streets and highways.
You want easier handling (AWD automatically adjusts power to each wheel, making it easier to drive than 4WD).
You're concerned about getting better fuel efficiency. AWD systems can be more fuel-efficient than 4WD systems, depending on the vehicle and driving conditions.
You're in an area with varied weather conditions like rain or light snow.
What is the difference between 4WD and AWD?
In short, here are the key differences:
Typically 4WD is a part-time setting, whereas AWD is normally always engaged.
4WD is turned on by the driver. AWD is run automatically by a computer in the car.
4WD is best suited for slow, technical off-road driving or challenging conditions like deep snow, where maximum traction is required. AWD is better suited for on-road use, particularly in areas with variable weather.
Check out some other curious questions:
Sources
Auffenberg Dealer Group. (n.d.). AWD vs. 4WD. Auffenberg Dealer Group. https://www.auffenberg.com/manufacturer-information/awd-vs-4wd/
Corby, S. (2018, April 19). All-wheel or four-wheel drive | what’s the difference? CarsGuide. https://www.carsguide.com.au/car-advice/all-wheel-or-four-wheel-drive-whats-the-difference-33194
Heaps, R. (2023, February 7). AWD vs. 4WD: Which Is Better?. Kelley Blue Book. https://www.kbb.com/car-advice/awd-vs-4wd/
JC Media. (2018). Quickly Clarified - AWD vs 4WD In 3 Minutes. YouTube. Retrieved December 28, 2023, from https://www.youtube.com/watch?v=W4qBZvEXBOo&ab_channel=JCMedia.
Stevens Creek Chrysler Jeep Dodge. (n.d.). 4x4 vs AWD. Stevens Creek Chrysler Jeep Dodge. https://www.stevenscreekchryslerjeepdodge.net/4x4-vs-awd.htm