How All Wheel Drive Works

What is All-Wheel Drive?

All-Wheel Drive (AWD) vehicles send power to all four of the wheels. This can be done in a number of ways but the end goal is improved traction and performance for the vehicle. While All-Wheel Drive is a more expensive option and uses more parts (more things that can break), there are some huge benefits. These include:

  • Better acceleration: With all four wheels putting power down (usually), gaining speed is easier.

  • More stable acceleration: With the power spread out between two axles there is less wheel-spin and consequently accelerating becomes more consistent.

  • Better grip in slippery conditions: Whether there is snow on the ground or heavy rain coming down, All-Wheel Drive will make the wheels grip more when accelerating or maintaining speed. All-Wheel Drive also makes the car much less likely to be stuck in mud or snow.

There is a slight distinction to be made between All-Wheel Drive and Four-Wheel Drive. In the US, in order for a vehicle to be labeled All-Wheel Drive, both axles must be able to receive power and rotate at different speeds simultaneously. If a vehicle has a transfer case, meaning that if both axles are receiving power then they will be forced to spin at the same speed, then it is Four-Wheel Drive, not All-Wheel Drive.

Many modern SUVs and Crossovers use All-Wheel Drive systems that are labeled Four-Wheel Drive. This gives axles the ability to spin at different speeds and has many practical applications, meaning manufacturers often reserve true Four-Wheel Drive for heavy-duty and off-road vehicles. They can be labeled as Four-Wheel Drive because they technically are, allowing all four wheels to drive the vehicle forward. Labeling an All-Wheel Drive drivetrain as Four-Wheel Drive also makes it appear more rugged and seem more like a dedicated off-road vehicle.

How Does All-Wheel Drive Work?

If the vehicle has a center differential, then the arrangement of the drivetrain resembles a Rear-Wheel Drive setup. The engine runs into a transmission and then back to the differential. Usually the engine is longitudinally mounted. Instead of connecting to the rear differential, like in a Rear-Wheel Drive vehicle, the driveshaft connects to the center differential.

A center differential acts just like the differentials in either axle. When one side of the differential is spinning at a different speed than the other, it allows one side to slip and the other side to receive more power. From the center differential, one driveshaft runs straight back to the rear differential while another runs to the front differential. Subaru uses a system that is a variation on this type of All-Wheel Drive. Instead of having a driveshaft go to the front axle, the front differential is built into the transfer case along with the center differential.

If the vehicle does not have a center differential, then the arrangement probably resembles that of a Front-Wheel Drive vehicle. The engine, likely transversely mounted, sends power to a transaxle. Instead of sending all of the power to the set of wheels under the engine, some is also sent to a differential on the opposing axle via a driveshaft extending from the transaxle. This functions similarly to an arrangement with a center differential, except that the transaxle almost always gets more power than the opposing axle. This allows a vehicle to use the All-Wheel Drive only when more traction is needed. This type of system provides improved fuel economy and is generally lighter. The downside is less All-Wheel Drive performance on dry roads.

Different Types of All-Wheel Drive

There are two main types of All-Wheel Drive used in vehicles today:

  • Full-Time All-Wheel Drive: This type of drivetrain uses three differentials to spread the power effectively between all four wheels. The wheels are all receiving power all of the time in this arrangement. Very well-liked All-Wheel Drive systems that have this arrangement include Audi’s Quattro All-Wheel Drive and Subaru’s Symmetrical All-Wheel Drive. Rally racing vehicles and their road-going equivalents use this type of All-Wheel Drive setup almost universally.

  • Automatic All-Wheel Drive: There is no center differential with this type of All-Wheel Drive. A transaxle powering one set of wheels directly puts most of the power into the front or rear axles while a driveshaft moves power to the differential on the opposing axle. With this type of system, the driver only gets the benefits of All-Wheel Drive in low-traction situations. This setup takes up less space than the alternative and allows the car to run more efficiently when acting as a Front or Rear-Wheel Drive.

Where is All-Wheel Drive Best Used?

  • Vehicles that see lots of weather: It’s easy to see why people living in very snowy or rainy areas would prefer All-Wheel Drive vehicles. They are less likely to get stuck and are more likely to get themselves unstuck if they do. When paired with weather-appropriate tires, All-Wheel Drive is near unstoppable.

  • Performance applications: Traction is important in high-powered vehicles. Solid traction allows a vehicle to be faster off the line and faster accelerating out of the turns. Every Lamborghini and Bugatti uses All-Wheel Drive. While there is a heightened risk of understeer (front wheels losing traction in a turn), modern engineering makes it largely a non-issue.

What Are The Drawbacks to All-Wheel Drive?

  • Sending power to both axles makes the vehicle less fuel-efficient. It has to use more power to get all of the wheels turning and more to make the vehicle accelerate.

  • The handling characteristics are not universally loved. While All-Wheel Drive allows consumers to get some of the best benefits of both Front-Wheel Drive and Rear-Wheel Drive vehicles, it can also exhibit the negative characteristics of both. Some cars may understeer when the front wheels get too much power in the corners while another may get oversteer when the rear wheels get too much. It’s really a matter of the driver’s taste and the particular vehicle.

  • More parts means more weight. Weight makes the vehicle perform worse and use more fuel. More parts also means more things that can break. On top of the fact that All-Wheel Drive vehicles generally cost more to start with, services and repairs may cost more down the road as well.

Is All-Wheel Drive Right for Me?

For people living in areas with lots of snowfall annually, All-Wheel Drive cars make sense for everyday use. The higher cost and worse fuel economy is worth the ability to go down the road in heavy snow or drive over a snowbank left haphazardly by a plowing truck. In such areas, All-Wheel Drive vehicles also have great resale value.

That said, many traction problems can be solved by season-appropriate tires. Most roads in most places are drivable often enough that All-Wheel Drive is rarely needed. All-Wheel Drive does not improve brake or steering performance in slippery road conditions, so the vehicles using it are not necessarily safer.


Next Step

Schedule Oil Change

The most popular service booked by readers of this article is Oil Change. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Oil Change reviews

Excellent Rating

(21,699)

Rating Summary
20,382
845
179
87
206
20,382
845
179
87
206

Matthew

33 years of experience
991 reviews
Matthew
33 years of experience
Volkswagen Passat - Oil Change - Hampton, Virginia
Matt always does a great job. Very professional. I look forward to my next appointment.... A++++++
Ford Expedition - Oil Change - Hampton, Virginia
I am so please to have Matt work on my vehicle, he is very friendly and personable, and always does a great job.

Greg

22 years of experience
37 reviews
Greg
22 years of experience
Audi A3 - Oil Change - Queen Creek, Arizona
Job well done! Greg was on time and professional. He treated my vehicle with care. He completed the job smoothly and so far so good. First time using Your mechanic and it was a pleasant experience. I will be looking into them again. Thanks Greg!
Ford Explorer - Oil Change - Scottsdale, Arizona
Greg was very friendly and professional. Communication was great, he let me know what he was doing. He went above and beyond to make sure everything was running smoothly. I would 100% recommend Greg!

LAVELL

27 years of experience
93 reviews
LAVELL
27 years of experience
Buick Encore - Oil Change - Oakland, California
Another home run! Really appreciate the flexibility regarding my service appointment. Due to my work schedule I desperately needed a late appointment. So grateful my car is receiving top shelf professional service. Replaced a oil pan drain plug that was seriously damaged and stripped by a competitor that will NEVER get my business again! All services were quickly completed. Thank you so much for another great experience with my.... Your Mechanic Lavell 5 ⭐️ Service consistently.

Brian

23 years of experience
483 reviews
Brian
23 years of experience
Porsche 911 - Oil Change - Ponte Vedra Beach, Florida
Brian is extremely knowledgeable and very personable and has taken very good care on my 911. I would recommend Brian to any one who has mechanical car challenges. I would recommend Brian to all My friends and family

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

5 Essential Things to Know About All-Wheel Drive (AWD)
All-wheel All-wheel drive (AWD) systems provide power to all four wheels, rather than only to the front or back ones. When driving, a majority of these systems have either a front or rear base, which means the power is focused...
What Does the Four Wheel Drive Warning Light Mean?
The four wheel drive light means your car has activated four wheel drive. If the Service 4WD light is on, there may be an issue with the system.
Comparisons of Drivetrains - FWD, RWD, AWD
The The drivetrain in a car is comprised mostly of the engine and transmission. The rest of it - the parts that take power from the transmission and send it to the wheels - these are the parts that really...

Related questions

I have a 1990 Chevy 4x4 short wheel base step side with an automatic transmission.

If the front drive shaft is spinning and not able to be engaged, then the chain in the transfer case could be broken. For the transmission to be in neutral in all the gears, but lock up in the park...

4 wheel drive will not engage 2010 Ford F150 4WD

Hello - it sounds like the 4WD-High actuator is not successfully engaging High-range as expected. There are many possible causes, bad servo actuator, transfer gear mis-alignment, transfer shift fork wear. For assistance, I would recommend transfer case inspection by a...

Im am looking for a car that is AWD and 5 speed but aside from a subaru i have no clue where to look.

Hello - lots of all-wheel drive with a manual transmission models to choose from: Chevy Equinox, Toyota RAV4, Honda CR-V, BMW 3-series, Audi A3, or A4 and so on. Happy motoring!

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com