What Really Causes Poor Fuel Economy in 4×4's?

Owning a 4×4 truck can be both wonderfully rewarding and painfully stressful, despite their many positive selling points, they often have a very poor fuel economy. Getting just a few miles per gallon (MPG) can add considerable fees onto your average monthly spend, as you’ll need to fork out for more gas than ever thanks to your truck’s inefficiency.

Having to spend an arm and a leg just to fill your tank with enough fuel is no doubt an infuriating procedure, but what actually causes a low MPG in 4×4 trucks and other 4-wheel-drive vehicles? Thankfully you needn’t be left in the dark for much longer, as this article lays out everything you need to know about poor fuel economy and why it takes place. Read on to find out more! 


Air Resistance And Aerodynamics 

One of the main reasons that a 4×4 truck has a lower MPG rate is its poor aerodynamics. The shape of a truck creates far more underbody air resistance compared with a 2-wheel-drive car, and this is something that cannot be changed or altered to improve your fuel economy. The aerodynamics of your truck will play a major role in determining your gas mileage, as it’s said that around 60% of the power that is needed to cruise at highway speeds is actually used to overcome air drag, which of course will be more intense for a larger vehicle. As drag also increases exponentially, this figure can also continue to increase even at higher speeds. Understanding the effects that aerodynamics has on an object will help you to figure out why it decreases fuel economy. 


Increased Body Weight 

A fairly obvious factor that can have a big impact on the number of miles per gallon that your truck can achieve is its total weight. Of course, the heavier your vehicle is the fewer miles you will be able to cover in a set period of time, as your vehicle will have to work even harder to move forward at speed. Inside a truck, you can expect to find a transfer case, front driveshaft, and front differential, and each of these pieces of machinery are heavy independently, never mind when combined together! The lighter your truck is, the better it’s fuel economy, so be sure to remove as much useless junk from your vehicle before you head out on the road. 


Larger Tire Size 

The larger tire size that most 4×4 trucks maintain can also have an effect on your vehicle’s fuel economy, as having bigger tires means that the engine has to work harder to push them around to achieve a full cycle. The smaller your tires are, the faster they will turn (with the need for much less energy), so driving around in a beefed-up custom-built 4×4 truck that boasts enormous wheels will of course reduce your expected MPG. It’s important to note that you need to pay attention to both the physical size and weight combined, as the total Kg will influence their speed and efficiency. Having a larger tire size can be beneficial for most truck users that choose to travel off-road or use their vehicle for work rather than leisure, however, if you’re aiming to improve your fuel economy then it’s better to source smaller tires for your vehicle. 

Rolling Resistance

When you drive, there’s an invisible force that’s acting upon your tires. This force aims to resist the motion of your tires from rolling on the surface, and it is better known as the rolling resistance. The rolling resistance of a 4×4 truck is far greater than that of a bog-standard 2-wheel-drive car, and that can explain why the fuel economy is so different! A truck has to inject far more power into pushing itself forward against the force of rolling resistance, as it’s much heavier and larger. This will mean that greater amounts of fuel are needed to ensure your 4×4 vehicle is able to reach acceptable speeds when driving, otherwise, your truck will be limping along at the slowest possible pace as it fights against the aforementioned rolling resistance. 

Learning exactly what causes poor fuel economy in 4x4s can help you to make appropriate adaptations and customizations to your truck to ensure you can benefit from the largest MPG levels. Building your own custom truck after taking in such knowledge will be even easier, as you can make the most informed decisions to promote the best possible fuel economy for years to come.

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