4×4 vs. AWD

What’s the difference and do I need it?

By Kristen Finley
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An illustration of the different drive systems, and where the power is drawn and distributed. Image made by Car and Driver.

4×4, or four-wheel drive, just like all wheel drive (AWD) are options that crop up on cars a lot more frequently than they have in the past. Nowadays, there are options such as part time and full time AWD or 4×4 systems, which can make coming to a decision a lot more difficult – not to mention, the terms are often incorrectly used interchangeably. With an overview of the basics, I hope to establish a better understanding for what situations call for which systems.

4×4

Four wheel drive (4×4) is a system designed to give a vehicle better grip and traction in low traction situations. This is achieved by allowing the wheels to spin at the same speed and rate, granting the vehicle more traction by removing the possibility of having a wheel slip. Having a wheel slip is akin to a person slipping on a wet surface – the shoe isn’t able to find grip between itself and the floor.

This is advantageous in areas that experience a lot of snow or involve a lot of mud. Without the loss of momentum and traction, a car can easily plow through snow and mud with little to no issue. Two wheel drive cars (think a Honda Accord or a Nissan Maxima) have difficulty in the snow and mud because only the front or rear tires (depending on whether it’s a front or rear wheel drive) get power from the engine.

Think of it this way, using the slippery floor analogy: if you feel yourself starting to slide around on a slippery floor, you’re better able to push yourself or maneuver your way off of the slippery surface using all four limbs. If you only use your two feet, it’s more likely that you remain in the same place struggling to find grip, sometimes resulting in a fall.

What calls for 4×4?

Most four wheel drive systems are part time systems, meaning that the system needs to be manually engaged. This means that when your car doesn’t have 4×4 activated, it’s a two wheel drive car. This makes it ideal for places that get snow because for most of the year, you have a car that’s two wheel drive and in winter, is a very capable car in sticky situations.

However, if you live in an area with a mild climate (such as California) 4×4 isn’t necessary unless you go off-road. Think going to Tahoe or Yosemite, where there’s snow. If you don’t make a lot of trips where there’s a threat of low traction, 4×4 is not an option you should consider, especially since vehicles with these systems need additional maintenance and adds cost.

It’s not advisable to use 4×4 in the rain either, since the system doesn’t do well on pavement – it’s designed for low traction situations ONLY. When a car is on the pavement, the wheels need to spin at different rates and speeds in order to complete tasks, such as making turns. If the 4×4 system is engaged when making a turn on pavement, it can cause damage to the already costly system.

Summary

4×4 is good at preventing loss in traction in the first place with the locking of all four wheels. Since they’re spinning at the same rate and time when the system is on, traction is hard to lose. However, you can ONLY use it when you’re in mud, snow, rock crawling, or loose dirt – since it’s not advisable to use on pavement. Which makes this system the most appealing and best suited for off-roaders.

AWD

All wheel drive (AWD) is similar to 4×4 in concept, but that’s where the similarities end. AWD enables all four wheels to spin at the same time, but when the system detects a loss in traction, it sends power to the wheel that’s lost the traction. Thus, all four wheels are spinning at different rates and times to help regain lost traction.

AWD is a full time system, meaning that it can’t be manually engaged or disengaged – it’s on all the time.

This kind of system is gaining popularity across manufacturers because it’s statistically shown to be safer than a two wheel drive system.

With all four wheels spinning at the time, it makes the vehicle a lot less susceptible to losing traction in the first place. For example: in rain, the reason two wheel drive cars tend to lose grip on rainy roads is because two wheels get more grip than the remaining two, which can end up in sliding over the water (hydroplaning). With AWD, all four wheels having traction make it a lot less likely to lose control.

What calls for AWD?

The advantage of AWD being a full time system is that it’s also suitable for snow, mud, and dirt. This system lends a sense of security to the driver knowing that their vehicle is equipped with a system that’s built to get them out of untimely or unexpected situations.

Like 4×4, it’s also a wise choice for people who enjoy an occasional unpaved road or winter adventure (since AWD cars aren’t required to wear chains).

Because an AWD vehicle is a lot more versatile and safe, the only argument against AWD is that AWD systems tend to make a vehicle more pricey, and they get less gas mileage. Since a 4×4 is only a part time system, mileage is only affected upon engagement – while the AWD eats more gas regardless.

Summary

AWD is better at recovering from a loss of traction. While all four wheels are spinning at the same time, which helps in preventing slippage, the rate and speed of wheel spin changes when there’s a loss of traction – which is safer in all scenarios, except for rock crawling. AWD is better for everyday use in areas with unpredictable weather, good when traveling to the snow and is the only system that’s good in the rain.

So, in short, AWD and 4×4 will meet the needs for a person who plans on taking it off-road or lives in an area that snows. If you’re a person who doesn’t plan on visiting areas with snow or going off-road, I don’t recommend either of these systems.

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