How does the weight of a trailer affect a car's fuel consumption?

Hooking up a trailer isn't just about adding cargo space — it's about reconfiguring your car’s entire dynamics. You change how it behaves, how it responds... and how much fuel it consumes. Especially how much fuel it consumes.

Towing a trailer has a significant impact on your fuel consumption. But understanding why it happens and how much it can increase requires going beyond the usual “more weight means more fuel” cliché.

More than just a matter of kilos

When you add a trailer, your car stops behaving like a self-contained unit. Every acceleration, every turn, every braking maneuver means dragging extra mass that changes the forces at play.

The engine needs to generate more torque. The gearbox shifts more often. And the brakes... suffer. The entire system operates under much more demanding conditions.

And it’s not just about starting off. The impact is constant: more weight = more rolling resistance = more fuel to keep up the pace.

But weight alone doesn’t tell the whole story.

Factors that increase fuel consumption

• Altered aerodynamics: if the trailer has tall sides or a boxy shape, it slices through the air like a wall. This creates continuous drag that increases exponentially with speed. On motorways, this effect is magnified, directly impacting fuel use.


• Weight distribution: a poorly balanced load isn't just dangerous — it forces the vehicle to make constant micro-adjustments, which require extra effort.


• Driving style: sudden acceleration, high cruising speeds, or late braking increases fuel consumption even without a trailer. With one, the effects are amplified.

The result? An increase that can range from 10% in light conditions up to 40% on demanding routes or with poor driving habits.

This is how fuel consumption skyrockets when you tow a trailer

Let’s say you drive a family diesel car that normally consumes 5.8 l/100 km. If you attach an 800 kg trailer with some cargo and take a 600 km trip on the highway, your fuel consumption might rise to 7.5 l/100 km. That’s over 10 extra liters in total.

Now add the price of fuel at €1.60 per liter. You’re spending an extra €16 per trip. And if you make that journey every two weeks? Over the course of a year, you’ll have spent more than €300 just due to the trailer.

Can this extra cost be reduced

Completely avoiding it? No. Reducing it? Absolutely. And significantly.

• Plan your load wisely: avoid too much weight at the back and secure any loose items that could shift the center of gravity.


• Control your speed: above 90 km/h, air resistance increases exponentially. Dropping to 80 km/h can lead to noticeable savings.


• Keep all tires properly inflated: low pressure = more friction = more fuel use.


• Avoid unnecessary acceleration. Smoothness is key.


• Check the trailer regularly. A misaligned axle or worn-out tire isn’t just dangerous — it increases fuel consumption.

The weight of the trailer doesnt just pull the car it pulls on your wallet too

But beyond the cost, there’s an important takeaway: when you tow, everything changes. From the way you drive to the engine’s efficiency. And understanding —not ignoring— those changes is what separates an occasional driver from a truly prepared one. It's not about avoiding trailers. It’s about towing with intelligence.