We’ve all seen the advertisements. Some big burly truck or crossover trekking through the backcountry, tearing up dirt and mud along the way. Or cruising up a snow-covered mountain road, whipping around corners only to end up at some Germanic resort for a day on the slopes. Along the way, the acronyms AWD or 4WD are presented across the screen, again at the end of the ad, proving that no matter where the weekend takes you or what the weather has in store, a trusted drivetrain will never steer you wrong.
But what does it all mean? You’d think that four-wheel-drive is just another way of saying all-wheel-drive right? Well, not exactly. There’s a different process in which sources of power are distributed in unique ways. Of course, AWD is a newer option, typically found on crossover SUVs and now even on some sedans and sports cars, while 4WD is reserved mainly for trucks and larger SUVs. Does that make one better than the other? Not necessarily. In the end, it all boils down to personal preferences and intended use. Let’s have a look at AWD vs 4WD in greater detail.
Your Common Denominator
A vehicle’s differential is a crucial piece of equipment that allows the vehicle an ability to make turns without compromising speed. For example, when making a turn, the wheels on the outside of the turn travel farther than wheels on the inside. This difference in rotation is made up with the help of the differential, which harnesses power from the drive shaft and distributes it where necessary to each wheel of the car. In the end, it all boils down to personal preference and intended use. In two-wheel-drive vehicles, the differential is located on only one axle since the drive shaft only needs to power that single axle. However, with an AWD or 4WD vehicle, variations of the standard differential are present to control torque to all four wheels of the car. And since the differential’s job is to direct power and torque down the drive shaft to the path of least resistance, without a locking or limited slip differential, climbing a snowy hillside or trekking through sand will only result in you spinning your wheels.
Understanding how two-wheel drive systems work will help you further grasp the complex systems that make up AWD and 4WD drivetrains.
All Wheel Drive
Equal Distribution of Torque
With an all-wheel-drive vehicle, similar to any other vehicle, the differential channels power from your engine toward the path of least resistance. However, with an AWD vehicle, the system can detect resistance on all four wheels, not just one axle. From here, newer AWD vehicles now feature a center differential that detects which wheel is experiencing the least amount of traction and therefore splits the engine torque away from that wheel and toward those with the most traction. The system is automated too, allowing drivers to travel from pavement to slippery, dirt-covered, or snowy roadways instantaneously without issues arising.
However, it’s not typically as capable in heavy off-road conditions because the front and rear axles cannot lock together, lessening the amount of traction an AWD vehicle can have in say heavy snow, deep sand, or steep inclines on the backcountry trails.
- Can automatically engage
- Splits engine torque toward wheels with most traction
- Versatile with both on and light off-road conditions
- Front and rear axles cannot lock together
- Struggles in heavy off-road conditions
Four Wheel Drive
Sheer Power and Aggression
On the flip side, 4WD boasts what AWD cannot. That is, it works by locking the front and rear axles together thus splitting the torque evenly between them. This is ideal for off-roading but is dangerous on dry pavement because locking the axles forces the front and rear wheels to rotate at the same speeds. And because your front and rear wheels naturally rotate at different speeds, this can cause the vehicle to spin out of control, not to mention the stress you’re putting on the powertrain.
Now if you really want to get intense with your off-roading capabilities, you can either purchase or install a center differential, similar to the AWD setup above but this variation has a locking mechanism. This device splits the power evenly between the front and rear wheels, thus doubling your traction. Obviously, this isn’t a necessary purchase but can certainly come in handy if you plan on hitting the desert badlands of Baja California.
Taking this a step further, you can set up a locking differential on each axle of the truck, forcing both wheels on each axle to rotate at the same speed. It’s with a locked center differential and locked differentials on both the front and rear axles of the vehicle that you’re able to evenly distribute torque from the engine to each wheel of the truck.
- Splits engine torque evenly between the front and rear axles
- Front and rear axles rotate at same speed for enhanced traction
- Ideal for deep snow, mud, and sand
- Requires manual engagement
- Can be dangerous if engaged on dry pavement
- Adds weight and complexity to a vehicle
Have Your Cake And Eat It Too
For most of us, we don’t need to commit to an intense Baja-capable 4×4. However, we’d still like to afford ourselves the opportunity to hit those backcountry trails over the weekend with enough time to make it into work on Monday, vehicle all muddied up in the process. Fortunately, there is a way for us to have our cake and eat it too. We’re talking about modifying an AWD vehicle in a way that provides similar advantages of a 4WD vehicle.
Simply put, you would need to install a locking differential on your AWD vehicle so that you have the ability to lock the engines power distribution in place in case you hit some really foul weather, or want to fully engage those muddied waters. Some vehicles actually come stock with this feature. For instance, Land Rovers often times come equipped a locking diff option. Also, new technology is allowing for automatic engagements of four-wheel-drive-like features on AWD vehicles. Traction control systems such as Crawl Control and Downhill Assist Control work to prevent differences in wheel speed given difficult terrain.
In the end, it’s all about your intentions and lifestyle. Is it worthwhile to shell out some extra dough on a competent AWD vehicle given your location and seasonal weather conditions? Absolutely. Is there a direct correlation between the amount of money you spend and vehicle dependence in any off-road conditions? Absolutely not. Skill, experience, and caution must be exercised during these situations. And solely depending on the car to get you out of a jam definitely isn’t the way to go about any level of exploration. In short, there is no better option between AWD vs 4WD. Clearly, it’s complicated, but understanding the basics will surely help you make an informed decision on the lot.