Why is My Car Using Too Much Fuel?

Buying a car is a big investment and, unfortunately, the expenses don’t stop there. With ongoing running costs and rising fuel prices, driving has certainly become pricier. However, many of us may unknowingly be making our driving more expensive than it needs to be.  

With a better understanding of what increases fuel consumption, most drivers could enjoy big savings. Even better, this only requires making a few changes to driving habits and being more proactive with car servicing and maintenance. 

In this article, we’ll be answering the all-important question: “When will my vehicle use more fuel?” Our comprehensive guide will break down why your car fuel consumption may have increased and give you expert tips on reducing your fuel costs. 

What is fuel consumption? 

In order to identify what is increasing our fuel costs, we first need to understand the meaning of fuel consumption and how it works. As the name suggests, fuel consumption simply refers to how much fuel (petrol, diesel or electricity) your vehicle is consuming. 

When discussing fuel consumption, we often talk about what Miles per Gallon (MPG) a car offers. This refers to how many miles a car can travel on one gallon of fuel. When you buy a car, the manufacturer will provide an MPG measurement, but, as we’ll find out, this can always change depending on various factors. 

According to 2024 research by Nimble Fins, the average fuel consumption in the UK is 38.8 MPG, although this does vary depending on the type of fuel. This research shows that petrol cars have an average of 36MPG, while diesel cars use 43MPG. Hybrid petrol cars have an average MPG of 53, while electric cars are by far the most efficient, with an average of 123MGe (Miles per Gallon gasoline equivalent). 

You may also hear people talking about Brake Specific Fuel Consumption (BSFC), which is used to measure and evaluate the efficiency of an Internal Combustion Engine (ICE). 

What’s most likely to waste fuel?

As we mentioned, numerous factors can cause increased fuel consumption. The good news is that most of these are within your control, so reducing how much fuel you use should be a reachable goal. 
Let’s explore 8 of the most common reasons why the fuel consumption of your car might be higher than normal. 

Poor tyre condition 

The condition of your car tyres plays an important role in fuel efficiency. Old, worn tyres and incorrect tyre pressure both cause rolling resistance to increase, which burns more fuel. 

Pay attention to the condition and age of your tyres. Generally, your tyres need to be replaced after 3-5 years, or 20,000-40,000 miles. However, if you notice signs of extreme tyre wear before then, don’t wait to invest in some new tyres. 

You should also respond quickly to any TPMS alerts and keep your tyres inflated to the recommended pressure.

Aggressive braking and accelerating  

Speeding around and braking and accelerating aggressively burn much more fuel than driving smoothly. Fuel consumption is at its highest when accelerating because the engine has to work extra hard to keep pushing the car forward. 

Easing off the acceleration and keeping your braking as smooth as possible is an easy way to conserve fuel. 

City driving and congestion 

Time and congestion have a huge impact on fuel consumption. Simply put, the longer your engine is running, the more fuel you’re using. 

According to TomTom’s most recent traffic index, London was the slowest city in the world to drive through in 2023. During rush hour, a 10km journey took 1 hour and 28 minutes on average, compared to just 49 minutes during optimal travel time.  

Idling 

Your car will also burn fuel even when it’s just idling; when the engine is running but the car’s not moving. 

Whether you’re stuck in the stationary rush hour traffic that we mentioned above, or you’re waiting to pick up the kids from school, turn your engine off to save that precious fuel. 

Wrong oil and filters

Your engine oil and filters have a direct impact on how hard your engine has to work. Using the wrong oil will decrease how well the components in your engine can move, putting additional stress on the engine and making it consume more fuel. Equally, clogged air filters will force the engine to work harder, again causing increased fuel consumption. 

Head to our blog for more information on what engine oil your car needs and make sure you arrange filter and oil changes as regularly as necessary. 

Faulty engine

The engine is the heart of your vehicle so, unsurprisingly, a faulty engine will have a large impact on your car’s performance and fuel efficiency. If your engine isn’t looked after properly and serviced regularly enough, it can suffer from various faults, from misfiring spark plugs to dirty fuel injectors. 

Make sure you keep up to date with regular car services so any faulty components can be replaced and be sure to arrange a diagnostic if you suspect problems under the bonnet. 

Faulty exhaust 

One of the key jobs of your exhaust system is to provide a good fuel economy, but if it’s not working properly, it will be unable to do this successfully. Common exhaust problems like leaks, faulty sensors or a failing catalytic converter will all have a negative impact on your car’s fuel consumption. 

Make sure to keep up with regular servicing and, if you spot any symptoms of an exhaust leak or other problems, take your car to a professional as soon as possible. 

Short trips

A car engine works most efficiently once it’s warmed up. When you do short trips, the engine doesn’t have a chance to reach its ideal operating temperature and therefore consumes more fuel. 

Worn clutch 

When your clutch becomes overly worn, it begins to slip. This means that the connection between the engine and wheels isn’t holding as it should. As a result, lots of power is wasted in the transfer from the engine to the wheels. 
Keeping up with regular servicing will help you identify early symptoms of a slipping clutch so you can have it replaced before it becomes a major problem. 

What reduces fuel consumption?

Now you know why your fuel consumption may be higher than normal, but what can you do to reduce how much fuel your car is guzzling? Here are some of our expert tips to easily improve your fuel economy.  

• Keep up with regular servicing – The single most significant thing you can do to maintain a good fuel economy is to keep up with regular servicing and be proactive with maintenance. If your car is using too much fuel, most of the time it’s because of a faulty or old component that needs repairing or replacing. Having regular car services will enable mechanics to identify and resolve these faults before they become problematic and costly.
• Drive smoothly and avoid heavy acceleration – As we know, braking and accelerating aggressively consumes more fuel, so try to keep your driving as smooth as possible. Avoid speeding and be gentle on the accelerator and brake pedal.
• Plan ahead – Where possible, planning ahead could save you lots of time in traffic which, in turn, will also save you fuel. Avoid travelling during rush hour where you can and, if this isn’t possible, look for alternate routes that avoid major congestion. 
• Invest in fuel-efficient tyres – If you’re seriously concerned about your car’s fuel consumption, it might be a good idea to invest in a set of fuel-efficient tyres. As the name suggests, fuel-efficient tyres are designed to provide better fuel economy than regular tyres by minimizing rolling resistance. 

If you think your car is due a car service, don’t put it off. You can easily book one today simply by searching for your local ATS centre and choosing a time and date that suits you.