Vehicle fuel consumption causes and troubleshooting

Increased vehicle fuel consumption can be caused by various mechanical issues, maintenance failures, and driving conditions rather than just engine problems. According to Marin Morava, a technical advisor for the Croatian Automobile Club (HAK), several specific components can impact efficiency.

Mechanical causes include faulty brake calipers or parking brakes that fail to release fully, creating constant resistance. Incorrect wheel geometry and low tire pressure also contribute to higher consumption and uneven tire wear.

Issues within the intake system, such as damaged air pipes in turbochargers or faulty sensors and actuators, can disrupt the air-fuel ratio. Furthermore, a malfunctioning exhaust system—due to leaks or improper parts—and problems in the fuel injection system, such as clogged injectors, are significant contributors to increased fuel usage. The engine cooling system, specifically a faulty thermostat, can also play a role.