A Car Suddenly Uses More Fuel, and the Engine Is Not Always to Blame

When a car suddenly uses a liter or two more fuel than usual, the engine is often the first suspect. But the cause may be simpler, and cheaper to fix.

Drivers should first confirm that fuel consumption has really increased. The trip computer may not be completely accurate, while traffic jams and several cold starts can sharply affect short-term averages. The most reliable method is to fill the tank, reset the trip meter, then divide the fuel added at the next refill by the distance traveled. Comparing several refills gives a clearer result than relying on one measurement.

Tire pressure is one of the first things to check. A drop of only a few tenths of a bar increases rolling resistance and forces the engine to use more energy to maintain speed. Unsuitable tires and poor wheel alignment can have the same effect. Roof racks and roof boxes increase aerodynamic drag, especially on highways, while unnecessary luggage has a greater impact in city traffic, where the car repeatedly accelerates and stops.

The car may also be braking constantly because of a seized caliper or a brake pad that remains pressed against the disc. Signs include weaker acceleration, faster deceleration when the driver releases the accelerator, the smell of overheated brakes, or the vehicle pulling to one side. A hot brake disc should not be touched, and repairs should not be delayed because the fault can damage other components and threaten safety.

Cold weather and very short trips naturally increase consumption. After a cold start, the engine needs time to reach operating temperature, and short journeys keep it in a less efficient mode. If it still fails to warm up after a longer drive, a stuck thermostat may be responsible. The temperature gauge may remain low and the cabin heater may work less effectively.