How to Improve Your Car's MPG: 12 Proven Tips for UK Drivers

Under-inflated tyres are one of the most common and easily corrected causes of poor fuel economy. The AA estimates that tyres inflated 8 PSI below the recommended level — which is surprisingly common in the UK — increase fuel consumption by around 4%.

The physics is straightforward: under-inflated tyres deform more as they roll, creating greater rolling resistance. The engine has to work harder to maintain speed, burning more fuel. The correct pressure for your car is found on a sticker inside the driver's door or in the owner's manual, and it varies by tyre size and sometimes by load (fully loaded vs. driver only).

Check tyre pressure monthly, when the tyres are cold (not after a long drive, as heat increases pressure readings). Use a quality digital gauge rather than the free ones at petrol stations, which are often poorly calibrated. Many UK petrol stations have air machines that cost 20–50p per use — worth every penny if it recovers 4% of your fuel spend.

Note: over-inflating tyres doesn't further improve economy and reduces wet-weather grip and tyre longevity. Stick to the manufacturer's recommended pressure.

Driving style has a larger impact on real-world MPG than almost any mechanical factor. The difference between aggressive and smooth driving of the same car on the same route can be 20–30% in fuel consumption.

Smooth acceleration: accelerate gently from stops and avoid flooring the throttle. In urban driving, smooth acceleration followed by engine braking (removing your foot from the accelerator and letting the car slow naturally) is far more efficient than sharp acceleration followed by hard braking.

Anticipation: look further ahead than most drivers do. If you can see a red light 200 metres ahead, take your foot off the accelerator now and coast towards it. You may find it turns green before you need to brake, maintaining momentum for free. If you do need to stop, the gradual deceleration recaptures more kinetic energy (if you have a hybrid) or at least doesn't burn fuel decelerating (in a conventional engine, many modern cars cut fuel injection completely when engine-braking).

Gear selection: drive in the highest gear that the engine can comfortably sustain. Modern petrol engines are typically happy from around 1,500 rpm; diesel engines even lower, from around 1,200 rpm. Many modern cars have gear-shift indicator lights on the dashboard — follow them.

Motorway speed: the relationship between speed and fuel consumption is non-linear. Aerodynamic drag increases with the square of speed, meaning the fuel cost of going faster increases disproportionately. Driving at 80 mph instead of 70 mph uses roughly 25% more fuel and legally exposes you to prosecution. Keeping to 70 mph on motorways is the single easiest high-speed MPG improvement.

Several routine maintenance items have a measurable impact on fuel consumption:

Air filter: a clogged air filter restricts airflow to the engine, forcing it to work harder and burn more fuel. The AA estimates a severely clogged filter can reduce economy by up to 10%. Air filters are cheap (£10–30) and typically replaced every 12,000–15,000 miles or annually.

Spark plugs (petrol engines): worn spark plugs cause incomplete combustion, wasting fuel. Iridium-tipped plugs last 60,000–100,000 miles and ensure cleaner combustion throughout.

Engine oil: using an oil with a higher viscosity than specified increases internal friction and reduces economy. Always use the viscosity grade in your owner's manual (e.g., 5W-30). Many manufacturers recommend low-viscosity 'fuel economy' oils (0W-20, 0W-16) in newer engines — these are not thin or protective, they're specifically engineered to reduce friction.

Fuel injector cleanliness: over time, deposits on fuel injectors reduce atomisation efficiency. A bottle of quality fuel system cleaner (added to the fuel tank) every 6 months can restore efficiency in older vehicles. Alternatively, using supermarket 'premium' fuels occasionally — which contain higher concentrations of detergent additives — helps maintain injector cleanliness.

Weight and aerodynamics are frequently underestimated factors in real-world fuel economy.

Roof bars and boxes: a roof box adds significant frontal area and disrupts airflow over the vehicle. At motorway speeds, this can reduce MPG by 10–15%. Remove roof bars and boxes when they're not in use — it takes 10 minutes and can save meaningful amounts on long motorway journeys.

Bike racks: a rear-mounted bike rack with two bikes increases aerodynamic drag substantially. A roof-mounted bike rack is worse. If you're doing a long motorway journey without bikes, remove the rack.

Boot clutter: many UK cars carry significant unnecessary weight in the boot — tools, sports equipment, bags. Every 50 kg of extra weight reduces fuel economy by around 1–2% across all driving types. Empty the boot regularly.

Air conditioning: below approximately 50 mph, the aerodynamic drag of open windows is less than the fuel cost of running the air conditioning compressor. Above 50 mph, the drag of open windows at speed becomes significant and air conditioning becomes more efficient. A rough rule: open windows in town, air conditioning on the motorway.