How to Improve Your Car's MPG

With UK petrol at 156p/litre and diesel at 188p/litre, getting more miles from every tank matters more than ever. The good news is that how you drive and maintain your car can make a bigger difference to real-world fuel economy than the manufacturer's official MPG figure suggests.

Here are 12 genuinely effective ways to improve your fuel economy — ranked roughly by impact.

1 Slow down on motorways Save up to 20%

Air resistance increases with the square of speed — so driving at 80mph forces your engine to work dramatically harder than at 70mph, for only a small time saving. Dropping from 80mph to 70mph typically improves fuel economy by 10-15%. From 70mph to 60mph saves another 5-8%. On a regular 200-mile motorway commute, this one change alone could save £500+ per year.

2 Check tyre pressure monthly Save up to 3%

Under-inflated tyres increase rolling resistance, meaning your engine has to work harder to maintain speed. Even 5-10 PSI below the recommended pressure can reduce fuel economy by 1-3%. Tyres naturally lose around 1 PSI per month, so monthly checks are worthwhile. The correct pressure is in your car's manual and usually on a sticker inside the driver's door frame — not on the tyre sidewall.

3 Drive smoothly Save up to 30%

This has the biggest potential impact of anything on this list, particularly in urban driving. Harsh acceleration wastes fuel; late braking wastes the kinetic energy you just burned fuel to create. Anticipate traffic, accelerate gradually, and try to maintain momentum. Smooth driving doesn't mean slow driving — it means reading the road ahead and avoiding unnecessary speed changes. Research suggests smooth driving can improve urban fuel economy by 20-30%.

4 Use higher gears earlier Save up to 15%

In a manual car, changing up at lower revs keeps the engine in its most efficient range. A good rule of thumb is to change up at around 2,000 RPM for petrol (2,500 for diesel). Many modern cars have a gear change indicator — use it. In an automatic, avoiding "sport" mode or aggressive driving will achieve the same effect.

5 Remove roof boxes and racks Save up to 25%

An empty roof box can reduce fuel economy by 10-25% at motorway speeds due to the additional aerodynamic drag it creates. Roof racks alone (without a box) add around 5-10%. Remove them when not in use — fitting and removing a roof box takes less than five minutes and the fuel saving over a long journey is significant.

6 Reduce unnecessary weight Save up to 2%

Every 50kg of extra weight increases fuel consumption by around 1-2%. Clear out heavy items you don't need — golf clubs, tool kits, and bags left in the boot all add up. A full tank of fuel weighs around 35-40kg, so filling up more frequently with less fuel has a marginal benefit on very short urban trips.

7 Use the air conditioning wisely Save up to 10%

Air conditioning increases fuel consumption by 5-20% depending on conditions. At low speeds, opening windows is more efficient. At motorway speeds, the drag from open windows outweighs the AC cost — so use AC at speed. Pre-cooling a parked car by opening doors briefly before setting off reduces how hard the AC has to work on the first part of your journey.

8 Service your car regularly Save up to 10%

A blocked air filter can reduce engine efficiency by up to 10%. Worn spark plugs cause incomplete combustion, wasting fuel. Fresh engine oil reduces internal friction. Regular servicing according to manufacturer intervals pays for itself in fuel savings over time — particularly for higher-mileage cars where wear begins to have a noticeable effect.

9 Avoid short cold starts Save up to 15%

Engines are least efficient when cold. A petrol engine can use twice as much fuel in the first mile of a cold journey as it does once warmed up. For very short journeys, walking or cycling is obviously better — but even combining short trips into a single outing (rather than multiple separate cold starts) makes a meaningful difference.

10 Use cruise control on motorways Save up to 7%

Maintaining a perfectly steady speed is more efficient than the subtle speed variations most drivers make naturally. On flat motorway stretches, cruise control can improve fuel economy by 5-7%. It's less effective on hilly roads where it can over-accelerate on descents and then work hard on climbs.

11 Turn off the engine when stationary Save up to 5%

Modern engines cost almost nothing to restart — the old advice about needing 30 seconds of driving to recoup a restart is outdated. If you're stationary for more than 60 seconds (waiting for a level crossing, sitting in a long queue), turning off the engine saves fuel. Many modern cars do this automatically via start-stop systems.

12 Buy fuel strategically Save 3-7p/litre

Supermarket forecourts consistently offer petrol 4-6p per litre cheaper than branded stations like BP, Shell, and Esso. On a 50-litre fill, that's £2-3 saved every time you fill up. The UK Government's Fuel Finder scheme (mandatory since February 2026) means all forecourts must publish live prices, making it easy to compare stations near you before filling up.