Canadians are buying more SUVs and light trucks than ever, and a lot of that has to do with their desire for all-wheel drive and four-wheel drive, a feature that is more widely available on these types of vehicles than it is on sedans and hatchbacks.
But the terms all-wheel drive (AWD) and four-wheel drive (4WD, or sometimes 4x4) are often used interchangeably, even by automakers themselves. Does that mean there are few or no differences between the two? Not at all, and in fact the distinctions can at times be as important as ensuring your vehicle isn’t damaged through unintentional misuse.
Here’s a closer look at the similarities and differences between AWD and 4WD systems, and an explanation of which one will best meet your needs depending on your situation.
AWD vs 4WD: What’s the Difference?
- All-Wheel Drive (AWD)
- Four-Wheel Drive (4WD or 4x4)
- Can You Get AWD and 4WD in the Same Vehicle?
- What is Torque Vectoring?
- Are AWD or 4WD Safer in Winter?
All-Wheel Drive (AWD)
All-wheel-drive systems can vary in complexity, but their job in simple terms is to feed an engine’s torque to both of a vehicle’s axles. This process can take place either all the time or only on demand.
A part-time AWD system will default to sending all of the engine’s torque to one axle, which equates to running in two-wheel drive. This could be either the front or the rear wheels depending on the vehicle, equating to running in front-wheel drive (FWD) or rear-wheel drive (RWD). When a loss of traction on the primary axle is detected, the AWD system engages the second axle on demand. The main benefit of a part-time system is better fuel efficiency. There was once a time when part-time systems were significantly slower to engage and respond, but in modern cars the difference is nearly imperceptible.
A full-time AWD system is engaged at all times with some amount of power permanently being sent to each of the vehicle’s axles. This can be as little as 1 to 2 percent to one axle in some systems that serves simply to keep it permanently engaged, or it can be a permanent 50-50 torque split. The benefit of a full-time system is that it’s always engaged, but it does use more fuel.
Regardless of whether a system is full-time or part-time, AWD is typically automated and doesn’t require any intervention from the driver to engage or remain active. In some vehicles, the differential that connects the driveshaft between the front and rear axle can be manually locked to force the system into permanent 50-50 distribution for short-term extra traction at lower speeds (for example, when driving through mud). Some vehicles will also come with selectable terrain management modes such as mud or snow snow/ice, which the driver can change between to adjust the traction control settings, among other things, and help the vehicle navigate through those conditions.
All-wheel drive is the better system for use on paved roads and in light snow because power is transferred through a differential, which allows the wheels to spin at the different speeds that are necessary for effective cornering. A wider variety of AWD vehicles is available from sedans to SUV and crossovers of all sizes and some lighter-duty pick-up trucks, giving the buyer more options.
Four-Wheel Drive (4WD or 4x4)
A four-wheel-drive system is more rugged and sends a fixed amount of torque to both axles at the same time. Like some all-wheel-drive systems, 4WD allows the driver to switch between part- or full-time operation, though in this system that adjustment is made manually and is necessary to prevent driveline damage. Four-wheel drive is considered more capable for off-road use and is therefore far more desirable among off-road enthusiasts and pickup truck owners.
Typically, a 4WD system has 2-High, 4-High, and 4-Low settings. 2-High powers a single axle, which equates to part-time operation, though here it’s entirely controllable by the driver. Like AWD, the primary axle can be either the front or the rear depending on the vehicle, though in this case it’s far more common for the rear axle to be the one that receives 100% of the torque in 2-High mode.
4-High mode pushes torque through the transfer case to lock the front and rear axles to the same spin rate, which is ideal for adverse road conditions such as snow or gravel. 4-Low uses an additional gearset within the transfer case to get even more torque to the wheels, making it intended for lower speeds and challenging conditions such as uneven surfaces or rock crawling.
The advantage of 4WD is that it gives the driver much more control over how the drivetrain is engaged, and its greater capability makes it the better choice for areas where more extreme or slippery conditions such as in off-roading or deep snow are common. The disadvantage is that 4WD should not be engaged in typical dry road conditions because the system spins all the wheels at the same rate, which stresses the driveline on cornering, not only making it more difficult but also potentially causing damage in on-road driving. This means that owners of 4WD vehicles will spend time in 2WD when owners of vehicles with automated AWD systems may not, which may also happen to coincide with better fuel economy.
Can You Get AWD and 4WD in the Same Vehicle?
Yes. A few vehicles offer all-wheel drive functionality integrated into 4WD systems. In this case, the AWD mode is sometimes labeled simply as “Auto.” However, some vehicles may not clearly differentiate between these types of systems, and it’s important to know the full capabilities of your vehicle before deciding to go ahead with a purchase. The best way to ensure you fully understand the system that’s equipped in your vehicle is to check the owner’s manual.
What is Torque Vectoring?
Torque vectoring adds another layer of control to an AWD or 4WD system where linked clutch units are added to an axle to allow either the left or right wheel to receive torque independently. In some vehicles, a single wheel will be capable of receiving 100% of the engine’s available torque through a limited-slip differential. This is most often a performance-oriented feature, as this system acts to roll a car around a corner more effectively by slowing the inside wheels or adding more torque to outside wheels to sharpen the vehicle’s cornering.
Are AWD or 4WD Safer in Winter?
All-wheel drive and four-wheel drive systems will help your car find traction and get going in adverse weather conditions. However, these systems do little if anything to help you with winter weather handling or with stopping. Those functions rely more on the tires and the contact point they create with the road surface.
This is why winter tires are just as important: they’re designed for better traction in snowy and icy driving conditions because their treads grip more effectively in these low-traction environments. Plus, their rubber is designed to withstand colder temperatures, being most effective at the temperatures where all-season tires begin to lose traction, that being at 7 degrees C or lower. All-wheel-drive and four-whee-drive vehicles still require winter tires; both have a role to play in keeping you safe and rolling during the winter months.