All-wheel drive. Four-wheel drive. We’ve all heard the terms, but what do they mean? And, which do you really need, if either?
Whether you’re shopping for a new vehicle, moving to a new area with rougher driving conditions, or just curious about your car’s capabilities, this guide is for you.
The truth is, these terms can be kind of confusing, especially since many car manufacturers have their own unique names for their 4-wheel or all-wheel drive systems. Understanding the basics can help you choose the right vehicle for your driving situation or make better use of your vehicle’s existing systems.
In this blog, you’ll find the answers to some of the most frequently asked questions about all-wheel drive (AWD) and 4-wheel drive (4WD), like:
Why is having AWD or 4WD important?
What is a powertrain?
What is all-wheel drive?
What is 4-wheel drive?
Which is better, AWD or 4WD?
Let’s take a closer look.
All-Wheel Drive vs. 4-Wheel Drive: Everything You Need to Know
Essentially speaking, vehicles move forward using traction.
Two-wheel, all-wheel, and 4-wheel drive are all systems for determining how much power is going to which axle on a vehicle. With two-wheel drive, a vehicle only ever sends power to one axle – either the front or rear. If that powered axle loses traction, the vehicle will have a hard time steering and moving forward.
With all-wheel and 4-wheel drive, there are ways to send power to the other axle. The difference between the two is about how and when that power is distributed.
Why is having AWD or 4WD important?
It isn’t, necessarily, depending on your driving situation!
If you’re someone who mostly drives in a city, in the suburbs, or on highways, and lives somewhere inclement weather isn’t all that common, you may never need either AWD or 4WD.
Most of the time, a two-wheel drive set-up works perfectly fine – if you’re driving on a clear, even road, you don’t need to worry about four-wheel or all-wheel drive. It’s when things get uneven or slippery that you need to think about the different set-ups.
Think of it like walking – most of the time, you just walk forward on your two feet and that’s perfectly great. It’s only if you, say, got stuck in the mud or slipped on ice or needed to climb that you really need to use your arms and hands to help you along. But if those situations arise, having the ability to call in extra power sure makes a big difference.
That means, if you’re someone who needs to drive off-road, haul heavy loads, or is regularly facing snowy and icy conditions, AWD and 4WD are more likely to come in handy.
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What is a powertrain?
To understand the difference between these two kinds of drive systems, we need to look at how vehicles work more generally.
The powertrain is the assembly of pieces that work together to put a vehicle in motion. It includes:
the engine, which creates power
the transmission, which uses gear sets to translate between engine speed and desired road speed
the drive shaft, which transmits power to the differential
the differential, which allows wheels to spin at different rates when turning or in case one wheel loses traction
and the axle shaft, which sends power from the differential to the wheels
In a 2WD vehicle, there’s one axle receiving power.
In a 4WD vehicle, there’s a front differential and a rear differential and you can choose different settings depending on driving conditions.
In an AWD vehicle, there’s typically a center differential, and power is sent to different wheels automatically. While the specifics vary from model to model, this is usually done based either on simple physics (as in a viscous or helical center differential where a physical change caused by wheel slip makes other parts of the powertrain react) or by a computer based on set parameters (called an electronic limited slip differential, which is becoming more and more common).
There are also systems in between that defy categorization, like those that send power to one axle or the other but never both at the same time – but that’s truly getting into the weeds.
What is all-wheel drive? (AWD)
An all-wheel drive vehicle has a center differential.
All-wheel drive is a system used to automatically redistribute torque based on traction. That is, it has the ability to send power to any wheel, and determines which wheels to send power to based on certain set factors. How exactly it determines where to send power and the system used to do so varies by maker.
Some AWDs are full-time (meaning they’re always sensing whether or not to change where power is being sent to) while others are part-time (meaning you can activate AWD capabilities, and otherwise have a 2WD vehicle).
Broadly, AWD is good for people who might encounter slippery road conditions, but not so much for off-roading and hauling.
What is 4-wheel drive (4WD)?
A 4-wheel drive vehicle has two differentials, one for the front and one for the rear.
Typically, when 4WD is activated, power is sent consistently to all 4 wheels, rather than the variable power of AWD, and the driveshaft locks.
4WD is usually a setting that can be turned on and off, and really shouldn’t be turned on when driving on a standard road. The extra friction can damage the vehicle’s tires and powertrain. Rather, 4WD should be engaged when driving on rough terrain, like driving through mud or snow, for climbing uneven and steep surfaces, or for pulling heavy objects.
In general, 4WD is preferred by people who spend a lot of time in the woods, driving unpaved roads, and taking on heavy duty tasks. It’s most common for trucks and SUVs designed for off-roading to have a 4WD drive option.
Which is better, AWD or 4WD?
Now that you understand a bit about how AWD and 4WD drive work and what they’re used for, you can decide which makes more sense for you.
Neither all-wheel drive nor 4-wheel drive is empirically better – they’re two different systems offering different pros and cons.
The short version is, if you’re looking for a vehicle that can handle a little extra mud, snow, ice, or heavy rainfall, but largely planning to stay on standard roads, AWD may well be the right choice for you. AWD can usually offer better road safety in inclement weather than a standard 2WD set-up, helping you stay out of road trouble.
That said, if you expect to find yourself in deep snow, significant mud, or heading off the beaten path, 4WD might be for you. 4WD is generally the best option for anyone planning to do heavy duty work with their vehicle or regularly drive through unpaved areas.
And one last thing to consider. These days, many different manufacturers offer their own patented versions of these features, each with a unique powertrain setup (and, in many cases, unique algorithm). If you’re thinking about purchasing a new vehicle, make sure you take time to look into the features being offered and how they work to make the right choice for your driving life.
And that’s everything you need to know about all wheel drive vs. 4 wheel drive.
If you already have a vehicle offering one of these features, you should be able to use and understand them better now.
If you’re exploring a new vehicle, the choice is yours. Which do you think makes the most sense for you?
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