Figuring out why your car is burning more fuel than usual can boil down to a number of reasons. It could be a mechanical issue or down to your driving style and bad driving habits. Getting the best fuel economy boils down to two key factors: that your car is performing at its best, and you are too.

To achieve optimum fuel economy from your vehicle, you’ll have to pinpoint the problem. You may need a little more air in your tyres, new filters, a basic repair, or you might benefit from driving at lower engine revolutions and making wiser gear changes.

Why does my car suffer from such poor fuel economy?

There are so many reasons why your car could be burning more fuel than normal. From the wrong tyre pressure to a slipping clutch, a faulty exhaust or burnt-out spark plug—all of these mechanical issues will cause your car to have to work harder, using more fuel to match your usual performance.

To get your car back to its ideal mpg, first, you need to find out precisely what the problem is, and then you need to fix it.

What are the common causes of poor fuel economy?

Low tyre pressure and faulty wheel alignment

Risk level – Medium

What to do – Check tyre pressures against the manufacturer’s recommendations and have your wheel alignment checked and balanced.

Whether your tyres are under or over-inflated, running them at incorrect pressures will affect your car’s performance and fuel economy. The correct tyre pressure should be shown on the panel inside the driver’s door or in your driver’s handbook.

Faulty engine issues

Risk level – High

What to do – A faulty engine could be sorted with a simple service, or it might take far more intensive work—depending on the issue. A diagnostic check should pinpoint the problem.

It may be something as simple as a misfiring spark plug, a faulty ignition coil, ageing connection leads, or even from overfilling with engine oil. Alternatively, there could be excessive carbon build-up, worn piston rings, or a faulty fuel injector. If there’s an issue with your engine, you should rectify it ASAP. A minor problem can soon grow into something far more serious and expensive.

Using the wrong engine oil and filters

Risk level – Low

What to do Book a service or an oil and filter replacement.

Using too thin or too thick engine oil affects how hard your engine has to work and also the wear it suffers. Either way, it can affect your fuel economy in the short and long term.

Clogged air and oil filters also force your engine to work harder to achieve your usual performance—all lowering your fuel economy.

Continuously running the air conditioning

Risk level – Low

What to do – Give the AC a break whenever you can.

Air conditioning units require plenty of power and leans on your fuel usage quite heavily. Using the AC only when you need it can result in a significant drop in your fuel economy. A faulty AC can also add to your fuel usage—book yours in for a repair today.

Short trips and city driving

Risk level – Low

What to do – Consider the alternatives.

You can’t do much about this one if your typical daily use is mainly city driving and short trips. A lot of start-stop driving doesn’t give your car a chance to get up into the gears where it achieves the best economy or often even up to its ideal working temperature. Maybe it’s time to consider switching to an electric vehicle or a smaller car designed for city driving?

A worn-out clutch

Risk level – High

What to do – Replace it immediately.

If the clutch is slipping, you’re not getting anywhere near the transfer of power from your engine to your drive system that you should be. Every clutch wears over time, and if it’s old and slipping, it’s time to get it replaced.

Excessive idling

Risk level – Low

What to do – Turn off the engine when stationary for long periods.

If you’re waiting for the kids outside school or for your other half to nip into the take-away and collect dinner, turn the engine off. If you leave the car idling, you’re burning off expensive fuel and adding to your poor fuel economy.

A faulty exhaust system

Risk level – High

What to do – Replace the faulty components right away.

From a leaky silencer to a dodgy sensor, there are plenty of parts in your exhaust system that affect performance—and fuel economy. Find the offending article and replace it immediately.

Poor driving habits

Risk level – Low

What to do – Learn to drive more efficiently.

Screaming around town at the highest revs is going to drain your fuel faster than an F1 car. Too much heavy braking and accelerating will add pounds to your fuel spend.

How can I get better fuel economy from my car?

For starters, if you believe your car is suffering from any of the above reasons, then have your local Fixter mechanic put them straight, right away. You might find that’s enough to get your car running back at a healthy mpg.

And, if you drive a little more like James May and a little less like Lewis Hamilton, then you’ll definitely save yourself a few pounds in the long run.

Can a service improve my car’s fuel economy?