More than 50 percent of new vehicles sold in the US come with either all-wheel drive or four-wheel drive setups. All-wheel drive options are available for many different segments, including minivans. Meanwhile, you will likely see a 4WD system on an off-road adventure vehicle.
The terms all-wheel and four-wheel are confusing. In a nutshell, think of all-wheel drive vehicles as street vehicles with some added traction when needed. And four-wheel drive units are almost always for off-road machines that are not entirely at home on the street. You can take a Ford F-150 4×4 on city roads, but you wouldn’t expect the all-wheel-drive Toyota Camry to blaze a new trail in the forest.
All-wheel drive systems:
- Usually powers one set of wheels–either in front or back
- All four wheels engage only when more traction is needed
- Commonly found in commuter-type street vehicles
A four-wheel drive vehicle:
- Can traverse rough backcountry roads with added traction
- Power commonly goes to all four wheels continuously
- Commonly equipped with high ground clearance, knobby tires, a shielded underbody, and a tow hook
AWD Adds Traction-On-Demand to a Street Vehicle
An all-wheel drive vehicle does not always send power to all four wheels. It depends on the road conditions.
In other words, an all-wheel-drive vehicle usually sends power to just one set of wheels, either the front or the back. But when the computers and sensors detect the need for greater traction, they engage all four wheels via a series of couplings and clutches.
2020 Toyota Camry XSE AWD tackling a snowy road. (Photo: Toyota)
For example, if the rear wheel starts slipping in the snow, the vehicle can transfer more power to the rear wheels to provide more stability and control. This is called a part-time AWD system.
When the Camry AWD senses slippage at the front wheels, it can send up to 50 percent of the torque to the rear wheels for more grip.
However, some manufacturers design all-wheel drive systems as full-time systems, meaning that power is constantly provided to all four wheels. A full-time AWD vehicle can improve traction on dry and slippery road conditions—although it usually costs a few miles per gallon.
Here’s a typical case: The 2024 Toyota Camry SE is rated at 28 mpg city and 39 mpg highway. But if equipped with an all-wheel-drive unit, the mileage drops to 25 city and 34 highway—about a 10 percent reduction in fuel efficiency.
A part-time AWD design limits the drop in gas mileage and wear on parts. The best aspect of a part-time AWD system is that the driver doesn’t have to choose between stability and fuel economy. The car’s computerized system sorts out the conditions and makes the best choice.
4WD Vehicles Are Meant for Off-Road Use
Many SUVs and trucks come equipped with a four-wheel drive system, sometimes called a 4×4. The main advantage of a four-wheel drive vehicle is its ability to traverse rough backcountry roads. A 4WD car or truck often features high ground clearance, knobby tires, and a shielded underbody. Four-wheel drive vehicles also often offer tow hooks and a winch for when drivers get stuck in between rocks or alongside riverbeds.
2024 Ford F-150 Raptor clawing its way up a dirt trail. (Photo: Ford)
Four-wheel drive vehicles also come in full-time and part-time varieties.
- A full-time 4WD puts the power to all four wheels continuously.
- A part-time 4WD vehicle is for the more serious off-road enthusiast. In this case, the vehicle is commonly driven only by the two rear wheels. But when drivers want extra traction, they pull a lever or push a button to engage all four wheels.
On some 4×4 vehicles, the driver can let the computer decide where to put the power. This is where the lines between 4WD and AWD get even blurrier. Some automakers believe 4WD conveys a greater capability (at a cost, of course), but it essentially operates like a part-time AWD system.
2024 Ford Expedition headed downhill. (Photo: Ford)
Gas mileage slips on 4×4 vehicles as well. For a 2024 Ford Expedition with its 3.5-liter V-6 engine, the standard rear-wheel drive unit gets 17 mpg in the city and 23 on the highway. But the 4×4 model gets one less mile per gallon for city and highway.
The advantage of a 4WD vehicle is its ability to handle rugged terrain while maintaining power and traction. However, a four-wheel drive vehicle has an even bigger fuel-economy penalty than an AWD car or truck. And 4WD trucks most definitely provide a stiffer ride.
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