Does 4-Wheel drive use more gas than 2WD? This article will discuss how the gas mileage differs from a 4WD driven in 4H vs 2H. We also compare the mpg between a 4WD vs. 2WD of the same make and model.
A 4-wheel drive will use more gas since it has more drivetrain components and weight compared to a 2WD of the same make and model. 4WDs have additional components such as an extra differential, a transfer case, and a front driveshaft. These components all add to the weight, friction, and rotational mass which negatively affects fuel consumption.
So now we know the short answer to the question, which is, yes it does, let’s look at HOW and WHY the unsprung weight of a vehicle can decrease your gas mileage. Also, we look at how friction and rotational mass affect gas mileage and performance.
Let’s dig in!
Table of Contents
Why Does 4-Wheel Drive Use More Gas (Less MPG)
So we’ve established that the gas mileage of a 4-wheel drive when driven in 2H, will be better than when the same vehicle is driven in 4H. What happens when we engage in 4H? Well, when you select 4H you are engaging additional drivetrain components to send power to the two extra wheels and differential, which is usually the front wheels. What happens?
Let’s look at them in more detail now.
4WD Drivetrain Components & Weight
So with 4H engaged you will essentially be activating or engaging the following components. Remember, they are all robust, weighty components that need to withstand the torque and power being transferred through the 4WD drivetrain system. That is why these components consist of really beefy, metal parts that are quite heavy.
The average weight of the additional 4WD drivetrain components:
|Front axle side-shafts
|Rotating the Front wheels
When you drive in 2WD (2H) mode with a traditional non-permanent 4WD, none of the above components are engaged and simply coast along. This means there is no resistance or drivetrain friction caused by these components since they are not involved in the forward propelling of the vehicle.
It is exclusively the transmission, rear driveshaft, rear axle, rear differential, side shafts, and wheels that are active when driving in 2H. This means improved consumption since less engine torque is lost having to rotate the additional components through the system.
So will a 4WD vehicle, that is driven in 2WD mode return better gas mileage than a 2WD of the same make and model? Well, if you consider all the additional components and the weight a 4×4 system adds to the vehicle’s overall mass, you are looking at extra weight in the region of roughly 250-350lbs, depending on the 4WD make, drivetrain component size, and other factors.
That might not seem like a significant amount of weight, however, they all require additional torque to physically move. Combine that with the internal resistance of all of the 4wd drivetrain components, resulting in additional fuel being used.
That said, a production vehicle that is released in a 2WD version will return the best gas mileage compared to the same vehicle produced in a 4WD model.
So best to worst gas mileage will be in the following order:
- 2WD Only Truck
- 4WD driven in 2H
- 4WD driven in 4H
- 4WD driven in 4Lo
Yes, 4Lo comes in last since you can easily see your mpg reading almost triple when using 4Lo. When I drive in 2H I get decent fuel consumption from my Amarok 2.0 BiTdi, returning 8.5L/100km easily in mixed urban driving. Once on the open road, it can drop to 7.5L/100. That is one of the main reasons why I opted for the VW Amarok, it was its excellent fuel economy, and it just made sense.
However, when I engage 4Lo when doing heavy off-roading, I can usually see the l/100km readings easily climb into the 23L/100km range. Note: always make sure you have sufficient fuel when going off-road.
The power reading from the flywheel to the wheels is different due to the drivetrain components and their weight. A significant amount of power is spent due to friction to spin gears, driveshafts, differentials, and joints just to transfer that power to the drive wheels. This is called driveline loss.
AWD vs 4WD Fuel Consumption
The modern AWDs of today mostly drive in 2H mode for improved gas mileage and only once traction is low will the AWD system distribute more torque to the front wheels in an attempt to regain traction. Most of the torque is sent to the rear wheels. This is made possible by utilizing either a multi-plate clutch box or an electrical motor that engages the AWD system.
Does Auto 4WD Use More Gas?
The 4-wheel drive Auto, or 4A, is a clever concept. In 4A mode, the vehicle initially powers only the rear wheels like in 2H. However, when traction is lost, the front wheels are instantly engaged to activate 4WD and regain traction.
This provides the benefits of both 2-wheel-drive for optimal gas mileage and the functionality of 4-wheel-drive when necessary. The computerized 4WD system and wheel sensors handle everything for you, making it incredibly convenient. Read more about the Ram 4A system here.
So, in conclusion, it’s pretty safe to say that a 4WD will never be as fuel-efficient as a 2WD of the same make and model. The weight, and friction, combined with rotating mass caused by the heavy drivetrain components of a 4WD will always result in lower gas mileage over a 2WD with less rotational components.
We are sorry that this post was not useful for you!
Let us improve this post!
Tell us how we can improve this post?