There are lots of simple tips to save on fuel, that cost little or nothing! Follow these ideas and a 10 - 15% fuel saving is almost guaranteed...

Slow down - boring but true. Above about 50 mph (80 kph), driving 10% faster will use between 10 and 20% more fuel, because air resistance is so much higher. Ask yourself if the time you save is worth the extra cost

Close windows and sunroof and take off the roof rack - reduces air resistance

Keep the air conditioning switched off unless you need it because the weather is hot or muggy (but do run it at least once a month, even in winter, or the compressor may fail).

(Around town, the most economical way to cool your car is by opening the windows. Driving at high speed, it's actually better to keep the windows closed but turn on the air conditioning).

Clear out the junk - carrying excess weight wastes fuel, so see if you really need to be carrying all that heavy stuff round with you

Anticipate - instead of accelerating madly and then having to brake hard for junctions or traffic jams, try and anticipate the hold-up and moderate your speed so you don't need to brake so much. Braking is just throwing energy away!

Keep tyre pressures up - sticking to the recommended pressure will save fuel and also give better handling. (Goodyear reckon if your tyres are 20% under-inflated you use up to 10% more fuel!) You can get "low rolling resistance" tyres, but the extra cost may not be justified by the fuel you save

Use a high gear - engines are more efficient at low speed than high speed, because so much power is wasted just moving the parts of the engine. As long as the engine isn't labouring (at a rough guide, don't go below 1500 rpm), then change up

Service your car regularly - not so critical on modern cars (fuel and ignition don't go out of adjustment in the same way), but worthwhile even so. (It's not just the engine - for example, if the brakes are binding slightly on, this can cause a big increase in fuel usage due to the increased friction.)

Use the right oil - I am sceptical about the various wonder additives you may see advertised, but you can see a small but significant improvement by using lower viscosity oil. 0W30 is better than 10W40, which in turn is better than 20W50. But don't use an oil that is too "thin" for your engine (consult the owner's manual), or you may cause damage!

Many people have reported benefits from using cruise control, though there is no obvious theoretical reason why it should help - perhaps the key is that it avoids you "drifting" up to a higher speed.

And, of course, ask yourself if the car is really the best way to make your journey. For trips less than a mile or so you may well be better off walking; up to a couple of miles cycling may be best. In a busy town or city it can often be quicker to walk than drive a short distance, and cars are at their least economical on short journeys. (If you must make short journeys, try and group them together so the car doesn't have a chance to get cold in the meantime.)

For certain trips (especially into and out of large city centres), public transport (buses and trains) may be the best option. Don't get me wrong; I am by any measure a "petrolhead", and nearly always find the car the best and most convenient way to get about. But sometimes the train or the bus is quicker or easier, and quite possibly cheaper too. It is possible to leave the car at home!

Techniques for super-economical driving are often known as hypermiling, and very dedicated drivers can achieve astonishing economy though rigorous use of such techniques. See, for example, EcoModder.

For more motoring money-saving ideas, see my page on choosing a more economical vehicle.