Hy does my Mercedes fuel average on highways instead of improving like it should?

Home > Gari Forums > Mercedes Benz Forums > Mercedes Benz A Class Forums > Mercedes Benz A Class Fuel Economy Forums

Hy does my Mercedes fuel average on highways instead of improving like it should?

Normally, highway driving should give better fuel economy, but some Mercedes owners in Pakistan notice a in mileage when cruising at high speeds 110–130 km/h on long drives. Is this due to high engine load, aggressive driving, wind resistance, o r turbo system issues? Could dirty sensors o r incorrect tyre pressure also affect highway fuel consumption in Mercedes cars?

Talha Kyanii asked on 20 Sep 2025 18:03:20 pm

1 Answer

76 views |

Gari Master - on 20 Sep 2025 18:05:24 pm

This is unusual, but possible causes include:

High-speed driving 120–140 km/h increases aerodynamic drag — even more if the car is fully loaded.

Turbo overuse: Turbocharged engines use more fuel at higher speeds o r under heavy acceleration.

Incorrect tyre size o r low pressure leads to higher fuel use.

Old fuel injectors o r oxygen sensors can cause poor air-fuel ratio, especially at steady cruise.

Recommended Checks:

Drive at steady speeds 90–110 km/h for best economy — Mercedes engines are most efficient around 1,800–2,200 RPM.

Inspect and clean fuel injectors if mileage stays low even with light driving.

Reset the ECU adaptive fuel trim after repairs o r fuel system cleaning a mechanic can do this.

Use cruise control when possible — it avoids unnecessary acceleration.