Fuel use rises quickly the faster you go, because air resistance builds up much faster than speed does. Dropping from 80 to 70 on a long run uses noticeably less fuel, and you'll only arrive a few minutes later.

Cruise control helps on a steady, flat motorway because it holds a constant speed. On hilly roads it can be wasteful, as it tends to push hard up the climbs.

Hard acceleration followed by hard braking burns fuel and wears your brakes. Look well ahead, lift off early when you see a red light or a queue, and let the car slow down on its own.

In a manual, shift up a little earlier and avoid revving the engine hard through the gears. In most modern cars, lifting off in gear cuts the fuel supply while the car is rolling, so it's more economical than coasting in neutral.

A cold engine uses more fuel, and a short trip means the engine spends most of it cold. Four separate five-minute trips use more fuel than one combined twenty-minute loop. Plan your errands into one run where you can.

If you're going to be stationary for more than a minute or so, switch the engine off. Idling gets you zero miles per gallon.

Short trips are also hard on diesels with a DPF, which needs longer runs to clean itself out. More on that below.

Underinflated tyres have more rolling resistance, so the engine has to work harder to move the car. They also wear faster and make the car feel less sharp.

Check them at least once a month, when the tyres are cold, using the figures in the handbook or on the sticker inside the door or fuel flap. Many cars list a higher pressure for when you're fully loaded or driving at speed, so use it for holiday trips and long motorway runs.

If your tyres are low on tread or unevenly worn, we can check them and fit new ones. Take a look at our tyres page.

Roof boxes and roof bars add drag at speed, and a roof box left on all year can make a real dent in your economy on motorway journeys. If you're not using it, take it off.

The same goes for the boot. Tools, sports kit and bags of "just in case" stuff all add weight. Keep the essentials (spare bulbs, a torch, jump leads, a warning triangle) and clear out the rest.

Air conditioning does use fuel because the compressor runs off the engine, but the effect is smaller than most people think. Around town at low speeds, opening a window is fine. At motorway speeds, open windows create drag, so air con is usually the better option.

Heated seats, heated rear screens and other electrical loads all put a bit more demand on the engine too, so switch them off once you don't need them.

Your engine relies on sensors to decide how much fuel to use. If an oxygen sensor, air flow sensor or temperature sensor starts giving bad readings, the engine can run richer than it needs to and burn extra fuel, often with no obvious symptoms other than the miles per gallon dropping.

An engine management light is the car telling you something is wrong. It's worth getting it read, because a cheap fix now can stop a bigger bill later. We use top-of-the-range Bosch KTS diagnostic equipment to find the cause properly rather than guessing.

Complex diagnostic jobs can take time, as we only have one master technician. If you're already seeing a warning light and want it looked at, it's worth booking ahead.

If you drive a diesel, a clogged DPF or a sticky EGR valve can hurt your economy. A blocked DPF makes the engine work harder, and the car may keep trying to clean it out (a "regeneration"), which uses extra fuel. Lots of short journeys make this much more likely.

If you're seeing a DPF warning light, struggling to get through a regeneration, or noticing worse economy and a loss of power, it's worth getting checked sooner rather than later. We offer DPF and AdBlue diagnosis and cleaning, so we can often find out what's wrong before it turns into a replacement.

Fresh oil of the correct grade reduces friction, which helps economy. Old, dirty oil does the opposite. Spark plugs on a petrol engine, and fuel filters on a diesel, also affect how cleanly the engine burns fuel.

Air filters get a lot of attention online, but on modern fuel-injected engines a dirty one has a smaller effect on economy than people claim. It's still worth replacing at the right interval, as it protects the engine, but don't expect miracles from it.

Our services start from £99 for an interim, £149 for a full and £249 for a major. We follow the manufacturer's intervals and we'll tell you honestly what needs doing and what doesn't.

A sticking brake caliper or a worn wheel bearing creates constant drag, so the engine works harder just to keep the car rolling. Look out for a pull to one side, a burning smell after a drive, or one wheel that is much hotter than the others.

Poor wheel alignment makes the tyres fight each other, which wastes fuel and wears them out. If your steering wheel is off-centre or the car drifts, get it checked.

The cooling system matters too. A thermostat stuck open stops the engine from reaching its proper temperature, so it keeps running in a fuel-hungry mode. If your temperature gauge takes ages to rise, or your heater never gets properly hot, it's worth a look.