5 Causes of Car High Fuel Consumption in Diesel and Petrol Engines


We all strive to get good fuel mileage in whatever vehicle we are driving. The majority of people on the road are driving vehicles powered by either a petrol engine or a diesel engine. Although diesel and petrol engines are different, they also have similarities as well. Some of those similarities pertain to problems that can occur which will cause them to consume too much fuel and make their fuel economy poorer.

Most high fuel consumption issues relate to some kind of engine problem, whether the problem is directly associated with the engine or something else in the car that is not allowing the engine to do its job properly. There are many for why this could happen in both diesel and petrol engine cars.

The Top 5 Causes of High Fuel Consumption in Petrol Engines

Below are the top 5 causes of high fuel consumption for vehicles with petrol engines.

  1. Carrying Excess Weight – One simple cause of high fuel consumption is when a vehicle is carrying too much weight, whether it has a lot of items in the trunk or in a trailer that it’s hauling. The more weight that’s being carried around by the vehicle, the more demand that is being put on the engine to generate enough power to move all of it. Whenever the engine must generate more power, it needs to burn more fuel in the internal combustion process. Therefore, you end up having to pump more gas because the vehicle uses more gas to satisfy its power needs.
  2. Bad Spark Plugs – When spark plugs get worn out, you will have a lot more engine misfires with your vehicle which will use up more fuel. You need to be sure to use the best quality spark plugs possible, so you can get the most miles out of them. Iridium spark plugs and platinum spark plugs are the two most preferred types.
  3. Dirty Air Filter – There are many reasons to have a clean air filter, but one big reason is to have a strong fuel economy. If your engine is filled with dirty air, then its internal combustion mixture won’t create as much power for the engine. This means it’ll use up more fuel just to perform the most basic driving needs. So, remember to change your air filter regularly.
  4. Low Tire Pressure– The tires on your vehicle need to be inflated to the proper amount of air pressure, usually between 32 PSI and 34 PSI on the majority of economy cars. If you’re driving a vehicle with low tire pressure on any or all the tires, it creates more wear and resistance for those tires. This causes the engine to work harder to make up for the pressure loss, which means more fuel will be used to power the engine for this purpose.
  5. Bad Oxygen Sensors – Your engine has oxygen sensors which keep track of the mixture of air and fuel in the internal combustion chamber. Based on what it senses, it tells the powertrain control module to either take away fuel or add fuel. But if the oxygen sensor does not work properly, the system will automatically add more fuel even if the engine doesn’t need it.

Read also: Symptoms of Blown Cylinder Head Gasket VS Cracked Block

The Top 5 Causes of High Fuel Consumption in Diesel Engines

Below are the top 5 causes of high fuel consumption for vehicles with diesel engines.

  1. Carrying Excess Weight – Like the petrol engine, a diesel engine can also consume too much fuel from carrying excessive amounts of weight.
  2. Bad Maintenance – Not only do your spark plugs need to be in good shape, but you must ensure that you regularly change the oil and replace air filters as well. Diesel engines can consume lots of fuel if any one of these is not done properly.
  3. Bad Gear Changing – Don’t change gears too quickly or too early. You will get better fuel mileage if the gear is changed prior to reaching 2,000 RPM. You’ll want a low RPM while changing gears because it enhances the fuel economy greatly.
  4. Driving Too Fast – Believe it or not, the difference between going 80 MPH and 70 MPH could mean the consumption of 25% extra fuel. That is why it is always best to just drive the speed limit and never go over it, even if it’s 10 MPH over it. Otherwise, you will be using up more fuel than needed.
  5. Air Conditioning – When you use the air conditioner, the diesel engine has more demand put on it. As a result, it must burn more fuel to meet this demand. If you roll down the windows, then it also burns more fuel because the open windows create a dragging effect which slows the vehicle down.

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