Driver Knowledge Tests

Improving your fuel economy: from the sensible to the extreme

Many of us look to buy a more fuel efficient car before we look at the habits we have that unnecessarily waste fuel. Sure, you can look at buying a small, more fuel-efficient car, but there are many other things you can do first. If you are learning to drive right now, learn these habits so that you save heaps of money by improving your miles per gallon. If you’ve been driving a while, even old dogs can learn new tricks!

Fuel economy tricks you should do

Moving unnecessary mass

Take a look in your boot and your glove box. Are you carrying around items that you don’t need or hardly use? Many people carry around spare clothes, sports equipment, rubbish and random items that they haven’t bothered to take out of the car. Even a child seat that’s not being used is adding to the weight. Many people carry 5-10kg of stuff they just don’t need.

Fill up more frequently

When you fill your car to the brim you can be carrying somewhere in the region of 16-20 gallons or 60-75 litres. If your car is a little lacking in power you will notice the difference from going from empty to full in that your acceleration will be blunted. 30 litres of fuel weighs 22kg which is the same as lugging around a small child. The more mass you have to move, the more energy it takes, and therefore the more fuel you burn. We don’t recommend leaving your car to get too empty, though, as this will pull the dregs of the tank through the fuel filter and will clog it up more quickly.

Tyres

Keep your tyres at the recommended pressure. Tyres that are slightly deflated have a greater rolling resistance which means the engine needs to work harder to turn them. Don’t over-inflate the tyres, though, because you will have less grip on the road as less of the tyre will be in contact with the road surface.

Anticipation

One of the biggest wastes of fuel is unnecessary acceleration. By looking further up the road you can anticipate when you need to lift off the throttle to slow down (which also saves your brakes as well as fuel). Try to smooth out stop-start traffic a little. Oh, and you don’t always have to win the traffic lights grand prix!

Vehicle tuning

Keep your vehicle tuned and maintained and it will run as efficiently as possible.

If you are changing your driving style, some vehicles have gearboxes which remember how you drive and it can take a while for them to adjust to a new style. If you find that your gearbox is holding your car in a gear that’s too low, look online to find out how to reset the gearbox (usually the easiest way is to remove the battery for a while to reset it)

Air conditioning

Using your air condition can burn 10-15% more fuel than not using it. The same applies for opening the window as it creates huge drag and your engine has to work harder. If you don’t need the air con on, turn it off. If it’s possible just to drive with slightly less clothing that’s an option, too.

Use eco functions

Some cars come with an eco mode which adjusts the throttle response, reduces the engine power or limits the air conditioning use. Or they use stop-start technology which allows the engine to be turned off when the car comes to a halt. If you know you will be sitting in a queue, stationary, for some time, then you can turn your engine off to save fuel, but if you don’t have stop-start technology your starter motor is not designed for constant stop-start operation, and you also have to bear in mind that with your engine off you have no control over the car.

Gamify your driving

If your car has a fuel economy gauge then you can try keeping it under a certain amount. If it has an instantaneous fuel usage readout you can use that to temper your heavy right foot.

Gears

If you’re driving a manual car then use higher gears for cruising. If you are driving along and your car is doing 4000rpm it’s probably in the wrong gear. A normal cruising range for a car at 60mph is 2000-3000rpm in top gear, depending on the car. There are cars which will be doing more than that, and others (often newer cars with 7 or 8 gears) that will be doing less.

Avoid bad weather

Water on the road creates extra drag on the tyres. If there are puddles try to avoid driving through them as your engine will have to work harder to maintain speed. If it is windy and your journey is headwind then you have extra force to overcome.

Minimise manoeuvring at low speeds

When your engine is cold, it uses much more fuel. Park your vehicle so that you can get away quickly without having to shuffle around. This means reversing into parking bays and making sure that you can drive out forwards.

What not to do

You can take some extreme measures such as ‘shaving’ your door handles (having them removed and smoothed over), buying smaller wing mirrors and taping up your panel gaps, but these are likely to cost far more than they’re likely to save. You can even remove detachable spoilers.

Unless you are driving a lot of miles changing your car often doesn’t pay for itself for a long while. For example, if it costs you three grand to change to a different car and your fuel economy is 20% better, how long will it take you to pay the difference?

Hypermiling is where you excessively and dangerously tailgate another vehicle to take advantage of its slipstream. This has some benefit, although negligible, but it’s far more dangerous because you won’t have time to stop if the vehicle in front has to brake suddenly.

Darren is an expert on driving and transport, and is a member of the Institute of Advanced Motorists

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