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10 ways to improve your fuel economy

If you need to save some money, looking at how and what you drive can help. Most of us don’t drive in the most fuel economical way, but we look to try to buy a more fuel economical car to compensate for this. Let’s look at 10 simple ways you can improve your fuel economy, and a few less practical ones.

Reduce the weight

Have a good look around your car for things that you are carrying that you just don’t need to be carrying. This includes rubbish, sporting equipment, spare clothes and other things that you lug about from place to place often only on the off-chance you need them. It uses fuel to move mass, so removing unnecessary items from your boot and glove box will help. You don’t need to go to extremes, though – you shouldn’t be removing door panels and rear seats.

Inflate your tyres

If your tyres start to go flat it increases the rolling resistance on the road’s surface because the tyre deforms more and more of the tyre’s surface is in contact with the road. The tyres take more fuel to rotate. Don’t over-inflate the tyres, though, because this reduces the contact patch between the tyre and road and can give you a lot less grip. Keep them inflated to the manufacturer’s recommended PSI.

When you have to change your tyres there are tyres which have a low rolling resistance.

Fill to a half-tank of gas

A full tank of gas can hold anywhere between 50-80 litres and, on some big SUVs, 120 litres. Petrol weighs around 0.7kg per litre so if you half fill your 60-litre tank you are carrying around 30 litres less than a full tank and that is around 22kg less. Of course, you’ll have to fill up more frequently, but you’ll benefit from better acceleration and fuel economy. Don’t let your petrol tank level get too low, though, because you risk pulling the debris and gunk from the bottom of the tank through your fuel filter and then you’ll have to pay to have that replaced. Always fill your tank as soon as the low fuel warning light comes on.

Engine tuning

An out-of-tune, neglected engine will not run as efficiently as an in-tune engine. Make sure that you get a service regularly and keep the oil and other fluids topped up.

You can also search online to see if there are reset options for your gearbox and ECU that might help as sometimes the shift points can be changed.

Climate control

If you have an air conditioning unit in your car, using it uses more fuel. Unfortunately, though, so does opening the window. If you can take off a layer of clothes rather than turn on the air con then you’ll save fuel. Just keep it tasteful! Still, opening the windows does use much less fuel than air conditioning, especially at slower speeds.

Built-in eco functionality

Some cars have an eco button that will adjust gear ratios, throttle response, power available and the level of air conditioning available. In a hybrid car the eco button will prioritise the battery. Some cars have start/stop technology which stops the engine when the car stops at traffic lights. These cars are designed to do this and have heavy duty starter motors that can be stopped and started over 400,000 times. If you don’t have this feature in your car, you could still turn the engine off if you know you’ll be sitting for a couple of minutes. However, bear in mind that you have no control over your car while you are sitting with your engine off.

Use the trip computer

Your trip computer will probably give you an average and instantaneous litres per 100km reading. You can keep an eye on this. The instantaneous one is useful because you’ll see just how much extra fuel you are using when you are accelerating as opposed to coasting.

Use the right gear

If you drive a manual car then make sure you are in the highest practical gear to get the best fuel economy. Automatic cars are almost always set up to give the best economy so you won’t need to worry about this if you have an automatic.

Anticipate the road ahead

By reading the road ahead such as when traffic is slowing or you are coming up to a corner that you’ll need to brake for, you can reduce your fuel usage. The most unnecessary fuel is used when you are constantly braking and accelerating and this happens a lot in heavy motorway traffic. By leaving a buffer to the car in front you’ll find that you can even out these variations in speed. This has two advantages. First, it will be more economical for you and a more comfortable ride. Second, because you are evening out the variations, every car behind you gets the benefit of this, allowing them to drive more smoothly – your act of fuel saving helps other people save fuel.

The only problem with this is that you’ll find people will dive in front of you a lot, but you can always just drop back a little and maintain the distance knowing that they’re the ones spending all those extra dollars filling up more.

Avoid the weather

When the roads are wet they provide more resistance against tyres. You’ll notice if one side of your car runs through a puddle that it pulls to that side. Try to avoid driving through puddles because it makes the engine work harder. You’ll often find that in heavier rain a long puddle will form in the two depressions caused by regular vehicle tyres. Driving just to the side of this can keep you out of the water. Be careful, though, because this part of the road can be more slippery immediately after it has rained.

Strong headwinds will add extra resistance to your journey. If you are driving a truck or motorbike you can purchase aerodynamic farings which will reduce your coefficient of drag.

Oddball ideas

If you really want to take it to the extreme you can perform some modifications on your car to reduce its wind resistance. Cars sometimes come with unnecessary spoilers which just increase air resistance and look good rather than supply any actual meaningful downforce. Other cars have large wing mirrors which can be replaced with smaller wing mirrors. You can even have your door handles removed and you can tape up your panel gaps. We don’t recommend this.

Another technique we don’t recommend is hypermiling. This is where you slipstream the vehicle in front – essentially an extreme form of tailgating that puts you at risk of running into the vehicle in front.

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Darren is a member of the Institute of Advanced Motorists and the NZ Motoring Writers' Guild

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Posted in Advice, Car, Heavy Vehicle, Motorbike
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