Causes of Car High Fuel Consumption in Gas and Diesel Engines

When it comes to high fuel consumption in any vehicle, the problem typically revolves around a faulty engine or some problem in another area which negatively impacts the engine in some way. It doesn’t matter if you have a diesel engine or petrol engine in your vehicle because high fuel consumption issues could happen in either one. However, there are some different reasons for why it would occur in each engine.

Gas Engine

In petrol engines, high fuel consumption can be attributed to worn out spark plugs, fuel filters or any other air cleaning feature of your car. These parts need to be replaced whenever they are old or worn out. You should also check the oxygen and throttle valve sensors too because they are responsible for managing the vehicle’s fuel system by ensuring the engine gets the proper mixture of air and fuel. The throttle sensor will send a signal to the fuel injection system as to how much power the engine is demanding. Therefore, if the throttle sensor is not working properly, then it could be incorrectly signaling the fuel injection system that it needs more fuel than is necessary.

Diesel Engine

As for diesel engines, the general cause of high fuel consumption are dirty air cleaners and fuel injectors. These two parts in any diesel-powered vehicle need to function properly during the combustion process in order for its fuel to burn properly. Also, it is crucial that you use quality diesel engine oil so you can get the most out of your fuel economy. If you use the wrong viscosity grade and have a much thicker oil than is recommended by the vehicle’s manufacturer, the moving parts within the engine are going to slow down and not move properly. This puts extra pressure on the engine and forces it to demand more fuel than it normally would.

Read also: The difference between dead battery and bad alternator

Fuel Efficiency Tips

If you want to increase your chances of having fuel efficiency in your vehicle, try to choose quality fuel stations when you go to fuel up your car. Some fuel stations mix chemical additives in with their fuel which will clean the intake valves found in petrol engines. With diesel fuel, these cleaning additives will help clean the injector nozzles found in diesel engines. Not only will these additives reduce the amount of waste buildup from the burnt fuel residue, but they will lubricate the engine’s internal components and upper piston ring so that it can function faster with less fuel needed.



    • Hi Paul did you get your mpg problem sorted. I’m havin same on an older car. Merc e250 coupe blue efficiency cdi. If you’ve had it sorted can you tell me what the problem was thanks

    • There are certain standards (set by the API in the USA and other agencies in other countries) in motor oil properties that have changed over time. Newer cars demand certain classifications of motor oil or you run the risk of performance problems or even engine damage. Your manual will tell you what type of oil your car needs. As long as you follow that, you have nothing to worry about. It doesn’t really matter what brand of oil you purchase, just that the oil follows those standards. More info can be found here:

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