All-wheel drive, four-wheel drive, full-time four-by-four. Even before getting into brand names like Rock-Track or quattro, the sheer number of options can all get confusing and overwhelming. Each system promises it is exactly what you need for traction in snow, sand, mud, and more, making vague claims like “more confidence” and “reassurance,” and more.
Are there any differences between AWD, 4WD, or 4×4, or is it all just marketing? There are some big differences, and we can explain.
Every System Has the Same Goal
No matter what the system is called, the point is the same: Send torque (we say power, but to engineers it’s torque) to both the front and rear wheels. That way, if it’s slippery, you have more traction. At least one tire should have enough grip, or the four tires combined have enough traction, to move your car, truck, or SUV.
To send power to four tires instead of two, each system needs a magic box of some kind, whether that’s a transfer case, a center differential, or a bevel box. The box sends some torque to the front axle and some to the rear, and that’s what separates the different system types.
4×4 Is the Original
Four-wheel drive, also called 4×4 or 4WD, was the original system for turning all your tires. The first gas-powered car with four-wheel drive was built in 1903, but it wasn’t until World War II and the invention of the Jeep for the U.S. Army that it became more common and eventually a household name.
A 4×4 system uses what’s called a transfer case to split power between the front and rear. In the system, a drive shaft comes from the back of the transmission and goes into the transfer case. One driveshaft comes out of the case to the rear axle, and another to the front.
The transfer case is a very old mechanical system. It has solid gears and often drive chains inside that split the power into two directions. It’s big, heavy, and sometimes noisy, making it perfect for pickups and body-on-frame SUVs like the Chevrolet Suburban or Toyota 4Runner where fuel economy is less important. It’s not exclusive to those, though, and unibody SUVs aimed at off-road use, like the Jeep Grand Cherokee and Range Rover, can use them as well.
Only 4x4s Can Get Lo
Most 4×4 vehicles use what’s called a two-speed transfer case, and this is what gives them low-range gearing. A two-speed, or low-range, transfer case is like having a small two-speed manual transmission inside the case. When it’s engaged in the low-gear range, it multiplies torque and lowers wheel speed. This lets off-roaders crawl slowly over rocks and obstacles at the cost of vehicle top speed.
These 4×4 vehicles have three modes: 2WD, where the drive to the front axle is not engaged, 4Hi, where both axles are driven, and 4Lo, which drives both axles and uses the torque-multiplying low-range gearing. There is also normally a neutral position, where neither drive axle is engaged. It’s ideal for flat towing or dinghy towing behind an RV.
AWD Vehicles Keep Things Loose and Easy When You Drive
AWD vehicles use some version of a center differential. Picture a rear axle’s differential, but instead of shafts coming out to the left and right, they go forward and backward out of the differential case.
Like a drive-axle differential, a center differential lets the wheels spin at different speeds. This way, the system can be used all the time, not just when it’s slick. The big problem with this system will be familiar to most pickup truck drivers, and it’s the problem of traction.
Open differentials will send power to the path of least resistance. If your front tires are slipping, an open center differential sends all of the power there. It’s not exactly helpful if you’re trying not to get stuck. If your center differential does the same thing, then only one of your four tires could be powered, and that’s the one that’s the most stuck.
Automakers have come up with loads of solutions to that problem in various ways. Automatic and computer-operated clutches, mechanical limited-slip devices like the torque-sensing (aka Torsen) differential, viscous couplings (where a fluid gets stiffer with pressure to transfer power), and whatever other inventions suppliers have brought out this year all have the same goal: to send some power to both axles even if one is slipping.
Why Most SUVs Have AWD
AWD systems are smaller and lighter than a 4×4’s transfer case, so they’re perfect for cars and crossovers where space and weight matter. They work well in snow, rain, and light sand, but they do have limits. Most front-drive–based systems, for example, can only send a portion of the torque to the rear axle, often well under 30%.
These low limits are fine when it comes to giving confidence to average drivers in bad weather, but they won’t cut it for serious off-road driving or rock crawling. They have trouble shifting enough power to get you going, and the clutches can quickly overheat, leaving you with two-wheel drive or even serious damage to the system.
What About Full-Time 4WD?
Full-time 4×4 systems blend the two different methods. They will use a transfer case–style box in the middle to send power front and rear with a mechanical connection. But they will also have a differential in the transfer case. It links the front and rear drive shafts while allowing the two to safely operate at different speeds.
Some use an open differential, which can lead to the same one-tire-turning problem as an open differential at the axle. Others use clutches to manage slip. Or on-demand mechanical locking to link the front and rear like a traditional transfer case. If you have a 4×4 system with an Auto mode, it’s really just a 4×4 system that engages when the vehicle detects slip, not a full-time 4×4 or AWD system.
Which System Is in My Vehicle?
Nearly all cars, crossovers, and SUVs will use an AWD system. There are some notable exceptions. Most of them are truck-based or truck-like SUVs, including GM’s Suburban and Yukon (and family), Ford Expedition, Ford Bronco, Jeep Wrangler, and similar.
Most pickup trucks, with the exception of models like Honda’s Ridgeline and Ford’s Maverick, use 4×4 systems. A full-time 4WD system is a 4×4 system, but without the ability to switch to 2WD. For example, all modern Land Rovers and Toyota’s Land Cruiser offer this.
Some vehicles will offer both 4×4 and AWD systems. The Cadillac Escalade, for example, has a 4×4 system (or RWD) in most of its versions. The high-power Escalade-V, aimed at drivers who want more sport than utility, has a system that’s more like an AWD unit for full-time use.
An easy way to tell if a vehicle you’re looking at has a 4×4 drivetrain versus an AWD system is the presence of buttons or even a separate shifter to engage the 4WD or activate the low-range gears in the transfer case. Some AWD systems may have a FWD/AWD engagement switch (though this isn’t common) but won’t have an option to select 4Hi or 4Lo.
Do I Want 4×4, AWD, or 4WD?
For most buyers, focus should be on the vehicle, not the drive system. For typical light snow, dirt, and sand, all systems work well, especially in combination with the right tires and a little help from modern drive modes.
If you want a car-like experience, AWD is your best choice. These systems, especially in more advanced and performance-focused vehicles, are lighter, more responsive, and more fuel-efficient. Perfect for most drivers and conditions, and you never have to think about them.
If you’re planning on more serious off-roading than the average person, especially overlanding, rock crawling, or trail running, you’re going to want 4×4. Full-time or not, the extra toughness and the guarantee of power to both front and rear axles are worth any potential fuel savings. Also, 4×4 systems are easier to upgrade later, with different gearing, locking differentials, and even just stronger parts from other vehicles.
The Outliers
If you have an EV or a hybrid, chances are it doesn’t follow any of these rules. Many hybrids, especially from Toyota, and all EVs are now what we call “through-the-road” AWD.
Instead of a mechanical link between the front and rear, through-the-road AWD systems have one power source in the front and another in the rear. In an EV, that usually means one (or more) motors in the front and one or more in the back.
The computer makes sure both turn the tires that have the most grip, and EVs with AWD are extremely effective. The hybrid systems used on the latest Toyota RAV4 and some others use the gas engine and the main hybrid motor to turn the front tires. A second, smaller electric motor drives the back tires.
This design is more efficient, but it also limits power because the second motor is often a small one. It’s a good solution for snow or rain, but again, not for serious off-roading.
AWD, 4×4, and Full-Time 4WD System Differences: Conclusion
The main differences between AWD and 4×4 are in toughness and how they transfer power. 4×4 is stronger and more reliably drives both axles; AWD is lighter, more agile, and can be much more high-tech.
For serious off-road driving, towing, and hauling, 4×4 is the one to pick. For everything else, it’s more about your tires and the specific system. Those will decide how deep into the unknown you can drive and make it back.
