AWD and 4WD can help you cover rough terrain with confidence.
In the past, all-terrain vehicles came with simple 4WD systems that turned them into able off-road machines. Rough around the edges at first, these manually-operated setups paved the way for more modern all-wheel drive (AWD) systems. Many of today’s top trucks, cars, and SUVs are equipped with 4WD or AWD. If you’re seeking an AWD car that matches your driving style, it’s good to know about these drivetrain options—and how they work.
To help you, we checked in with a CarMax associate in Chicago, IL, where weather can get extreme. He has appraised thousands of vehicles, and he has some great insights about AWD and 4WD—and suggestions about the system that’s best for you.
The pros and cons of AWD and 4WD
"...the two biggest factors when choosing 4WD and AWD are the weather where you live and your driving style."
- CarMax Senior Buyer
Our expert is a senior buyer at one of our Chicago-area stores, and he has appraised thousands of cars and trucks in his 13 years with the company. Lots of them have been 4WD and AWD vehicles. He knows what he's talking about when he advised customers! He says the two biggest factors when choosing between 4WD and AWD are the weather where you live and your driving style.
Four-wheel drive vehicles have been around for decades, but they’re certainly not outdated. Manufacturers continue to choose dedicated 4WD systems for their rugged trucks and utilitarian SUVs due to their balance of performance and value.
If you want total control of your vehicle’s driving characteristics, 4WD is the best choice since you have to activate the different modes manually. Our buyer says that if you get super-stuck, the extra-low or 4-low gear found in a 4WD really comes in handy—and this isn’t an option in an AWD vehicle. Beyond controlling the way your vehicle drives, activating the 4WD mode only as needed could also reduce your overall fuel consumption. Plus, the extra traction provided by 4WD gives you an edge when you’re towing on slippery surfaces. Beyond controlling the way your vehicle drives, activating the 4WD mode only as needed could also reduce your overall fuel consumption.
Our expert says if you wouldn’t use 4WD more than a couple times a year, you might be better off with AWD. Living in colder climates where snow and ice are more common is a strong reason for choosing 4WD over AWD. In addition, if you don’t pay close attention to the driving surfaces you’re covering in a 4WD vehicle, you may experience the shuddering, jolting sensation caused by wheel wind-up. This sensation not only feels terrible—it could damage your vehicle’s differentials and axles. As a result, you must always commit to paying close attention to the road conditions, and take the time to activate the system, to keep your 4WD vehicle in good working order year after year.
“If you don’t want to deal with concerns over changing gears yourself, AWD probably meets your needs better...with AWD, the car can detect a slippery surface before the driver does.”
- CarMax Senior Buyer
Modern AWD systems have plenty of bells and whistles, but that doesn’t mean they don’t have drawbacks. Thankfully, the optimal balance of performance and convenience afforded by AWD drivetrains tends to win out over the perceived drawbacks.
Even the most basic AWD system does all the thinking and adjusting for you. You can drive over any surface or through extreme weather conditions without selecting 4WD mode or worrying about turning it off afterward. Plus, you won’t need to worry about differential or axle damage from wheel hop because the AWD system keeps everything under strict control.
“If you don’t want to deal with concerns over changing gears yourself, AWD probably meets your needs better,” our advisor in Chicago says. “With AWD, the car can detect a slippery surface before the driver does.”
ConsSince AWD makes use of several integrated systems, a full-vehicle diagnostic test may often be needed to pinpoint exact part failures and appropriate repair procedures.
Top 4WD vehicles
Best AWD vehicles
Mechanical components and how they work
When you’re driving a vehicle equipped with on-demand 4WD, you can select 4WD drive mode yourself. This locks the differentials together so your wheels will spin at the same rate. You’ve got a differential at the center of your car’s front axle and another at the rear axle to control the wheels’ rate of spin. A transfer case distributes your engine’s power through these two differentials. Some 4WD systems let you select a low or high gear to further control the power distribution.
With this type of system, the wheels will spin together, which negates the power loss that occurs when one wheel slips on low traction surfaces, such as ice, snow, or loose dirt. An unfortunate drawback of this setup is windup, or wheel hop, when turning on high-traction surfaces. As the 4WD vehicle turns on non-slip surfaces, the axles start to turn at different rates, causing the wheels to skip across the road surface.
Since this effect could damage your vehicle’s drivetrain, you’ll need to be sure to disengage 4WD as soon as you return to paved road or non-slippery driving conditions. On older 4WD systems, like the ones used on early Ford F-150 trucks, this meant exiting the vehicle to manually turn the locks on the front wheels or briefly putting the vehicle in reverse to release the differential locks.
When full-time 4WD and AWD systems were developed, manufacturers added a center differential that automatically controls power distribution to the wheels.
A center differential automatically detects slippery situations and directs power where it’s needed most, rather than let it travel down the path of least resistance as would naturally happen. This linking differential, found in AWD SUVs like the Ford Explorer, monitors the drive wheels and immediately sends power to the other differentials upon noticing the system slipping.
Eventually, vehicle manufacturers added electronic control systems to help this AWD and 4WD to be even smarter—to allow gear ratios and power distribution patterns to change on the fly. Understanding the difference between AWD and 4WD electronic control systems can help you select between the various modern vehicles on the market today.
Electronically-controlled 4WD and AWD
As production vehicles began to make more use of electronic control modules (engine management, anti-lock brakes), it was only natural that electronics would be employed to enhance the performance of 4WD and AWD systems. For on-demand systems, electronic controls replaced the archaic manual switches and operations of yesteryear. That’s right—the days of climbing out of your truck to dial the front wheels into four-wheel drive-locked position are no more! Modern part-time 4WD vehicles, like the Chevy Silverado 1500, now have a button or lever in the cab that instantly links the differentials to engage four-wheel drive.
Electronic control systems found in full-time AWD and 4WD vehicles smartly determine the best gear ratio and power split to use on the fly. While driving down the road, the system monitors for wheel slippage using the anti-lock braking system (ABS) sensors. Changes in wheel speed activate the control system to help make sure the vehicle maintains traction in all driving and weather conditions. The system may also apply the brakes to decrease wheel slippage as the powered wheels propel the vehicle forward.
If the car’s control module links to a traction control system, it may also engage to automatically decrease engine power or adjust the steering mechanism in tandem with other corrective operations. These adjustments occur within a fraction of a second to minimize the skid and skip sensations of yesteryear and keep the vehicle under control.
As you search for your ideal 4WD or AWD car, there are a few key things to keep in mind.
Manufacturers sometimes use their own naming designations to identify their vehicles as 4WD- or AWD-equipped. For example, the Mercedes-Benz C300 has an AWD system called 4MATIC®, while Audi uses Quattro® for its all-terrain drivetrain. When choosing between the top AWD and four-wheel drive cars, keep this naming system in mind to avoid overlooking a suitable vehicle.
The amount of power distributed to each axle or wheel varies according to the settings determined by each vehicle manufacturer. Four-wheel drive vehicles typically utilize a 50/50 front-to-back split to consistently apply power to the ground.
All-wheel drive vehicles will split the torque front to back and side to side using a ratio determined best by the center differential. As an example, Subaru vehicles may utilize a 90/10 torque split to send power from the front axle to the rear axle in an effort to navigate across extremely slippery surfaces without sliding around.
Whether you choose a 4WD or AWD car, truck, or SUV, you should abide by the manufacturer’s maintenance requirements to keep your vehicle in optimal condition. The repairs for these vehicles may be slightly more demanding than front- or rear-wheel drive cars and trucks due to their increased utility and performance characteristics. For example, if you damage one tire, it may be necessary to replace two or even all four at the same time to avoid damaging your axles or differentials.
The history of AWD and 4WD
On-demand 4WD arrived on the automotive scene in the late 1800s to dramatically improve the handling of hill climb racecars. The practical functions of this tech made it a permanent fixture on military vehicles soon after. During the early years of all-terrain drivetrain development, Jeep's 4WD military and civilian trucks became known as go-anywhere vehicles. To push the limits of this tech, other manufacturers began to equip their purpose-built vehicles, such as off-road trucks, with full-time 4WD.
In the early 1960s, a British car company called Jensen created the FF sedan—the first passenger vehicle to utilize full-time AWD in a sports car platform. At this point, this drivetrain tech was spreading more rapidly as manufacturers began to experiment with all-terrain builds in unlikely platforms. By the motorsports-crazy 1970s, it became common practice to equip sports cars with 4WD to maximize their performance in all weather and road conditions.
Once vehicle manufacturers fine-tuned their torque distribution ratios and mechanical powertrain components, full-time AWD was born. Today, vehicles equipped with AWD are available from nearly all vehicle manufacturers. Four-wheel drive systems are still quite popular in the production vehicle market as well. This means you must choose between these two drivetrain configurations when you’re looking to upgrade to an all-terrain capable car, truck, or SUV. Learning more about how these systems work will help you select the best vehicle for your needs.