AWD cars do use more gas when compared to their RWD or FWD counterparts of the same make and model. This is down to many different factors such as increased weight, more drivetrain components, and additional friction and rotational mass created by those additional components.
Rotational or unsprung mass creates a substantial difference when it comes to fuel efficiency. A great example of this is often seen with high-end sportscars which tend to use carbon-ceramic brakes and magnesium/carbon wheels which all decrease the unsprung mass significantly.
If there is less mass that needs to be rotated, it means that the engine will not work as hard as it otherwise would thus decreasing the need for fuel. Driveline loss is also an important factor because a significant portion of pulling power is needed to spin all the drivetrain components which also negatively affects fuel efficiency.
Whenever manufacturers post their fuel efficiency numbers, those are usually associated with the best possible scenarios and driving environments. That means that it’s more important to drive efficiently than it is to opt for AWD or RWD/FWD.
State-of-the-art AWD systems and fuel efficiency
An AWD system is designed to maximize efficiency, but the ability to succeed at doing so is highly dependant on the way the car is being driven. This means that most modern-day AWD cars are not AWD all the time.
The whole point of an AWD system is to be either RWD or FWD for the majority of situations which only means that all four wheels are being driven if the situation deems it as necessary, or in other words, a car is AWD only when you need it to be in order to be safe.
If you are mostly driving on the highway, your AWD car is hardly ever going to be AWD. If your car has additional modern-day fuel-saving technologies such as cylinder deactivation technology or mild-hybrid technology, it means that even an 8-cylinder 600hp 2-ton luxury sedan can be efficient if you drive it as such.
AWD systems are inherently less efficient
Even though you can theoretically be more efficient with an AWD car, if you are driving your car the way you always drive any other car, it usually means that an AWD car will be less fuel-efficient.
The main reason why AWD cars are less fuel-efficient is down to the increased weight of the car, and the logic behind this is simple. If you are operating with a set amount of energy, and you try to carry loads that differ in weight, it’s understandable that the lighter you are, the longer you will carry that load.
Another reason is driveline loss because the energy created by the engine has to go through the transfer case and the front driveshaft, the front axle, front side shafts and then reach the wheels themselves. If you are driving an FWD/RWD car, then these components only coast and do not require pulling power.
Because these components serve such a vital purpose, they are also incredibly heavy in order to be reliable and capable of continuous strains.
Why you should opt for AWD
Even though an AWD car is less fuel-efficient and it costs more than a RWD/FWD car, there are many reasons why an AWD car is an overall better option. An AWD car is more surefooted and safer in almost every situation which is paramount as far as family cars go.
No matter how skilled you are driving a RWD/FWD car, an AWD car will almost always outperform those cars because it holds onto the surface better. As such, this also benefits performance and braking as well because there is more weight pushing the tires to the ground.
Be that as it may, the main reason to opt for an AWD car is that it performs way better in cold and slippery conditions. Even with proper tires, sometimes a car can not deal with slippery conditions making the driving experience that bit more stressful.
On the other hand, an AWD car oozes surefootedness when equipped with proper tires, and there is hardly ever going to be a situation or a winter obstacle you will not be able to traverse. Finally, almost all higher-end cars are simply better if equipped with AWD because they are safer, faster, and more confident inducing.
Which cars need AWD?
A small portion of cars these days come with AWD as standard, most cars are either available with AWD as an option, or they are not available with AWD at all. This poses the question if one should opt for an AWD variant even if it sometimes costs a few additional grand.
If you are buying a larger SUV, a large sedan, or a family vehicle, it’s always better to opt for AWD both for safety reasons and the ability to rely on your car whenever the weather deems it appropriate. On the other hand, if you are buying a compact hatchback or sports car, don’t opt for AWD if it’s not necessary.
Why do I need AWD?
You need AWD if you primarily reside in an area that gets lots of snow, ice, and rain during the year. You should also opt for an AWD car if you are someone who regularly visits the countryside where roads are not all that sophisticated and adequately paved.
If you are primarily using your car for longer journeys on the highway, and you don’t experience lots of weather adversity, you don’t need an AWD car. However, it can be useful to opt for one no matter the circumstances if an AWD variant of that car brings better value on the 2nd hand market.
Can I turn off AWD?
Most cars are AWD all the time, which means that you can not entirely disengage the AWD system. 4WD cars are designed to be able to switch between 2WD or 4WD depending on what you want. 4WD cars are almost always older off-road SUVs, which means that they are not as accessible or necessary as AWD cars are.
Some cars like the BMW M5 or the Mercedes AMG E63 S enable you to completely disengage the front differential for the car to be 100% RWD, but engaging this feature only makes sense in closed and safe environments such as tracks or drag strips.