Fea­ture: how to save fuel

CHANG­ING YOUR DRIV­ING STYLE AND SOME AS­PECTS OF YOUR VE­HI­CLE CAN GO A LONG WAY TO CUT­TING COSTS

Car (South Africa) - - CONTENTS - BY: Peter Palm

AS the fuel levy and the price of crude oil in­crease, all while the value of the rand de­creases and in­fla­tion climbs, we’re left with less dis­pos­able in­come each pass­ing year. How can we ease the pain? Well, we could moth­ball our cars and ride bi­cy­cles or use pub­lic trans­port … or we could all switch to scoot­ers or 125 cm3 mo­tor­bikes that sip 2,0 L/100 km. But then there’s the wet-weather fac­tor and the dan­gers in be­ing on the road with­out the ben­e­fit of a roof for pro­tec­tion. So we keep on driv­ing be­cause our cars are safe and con­ve­nient. Do we have some lee­way to cut the costs? The an­swer is yes and here’s how to do it.

1) RE­DUCE YOUR SPEED

The faster you go, the more fuel your car uses and a lot of this has to do with drag. With in­creased speed comes more drag. Even worse, drag goes up at the square of your speed. In other words, if you dou­ble your speed from 60 to 120 km/h, the drag you must over­come (by burn­ing more fuel) will in­crease four­fold.

2) SWITCH OFF THE AIR-CON

Run­ning the re­frig­er­ant com­pres­sor sucks en­gine power, which in turn uses more fuel. Use it only when you can’t bear the heat.

3) COAST DOWN­HILL AND SWITCH OFF CRUISE CON­TROL

If you have a vac­uum gauge fit­ted or own a car with an econome­ter (they’re largely the same thing), you would no­tice the dif­fer­ence in fuel con­sump­tion on as­cents and de­scents. The in­let-man­i­fold pres­sure drops when you ac­cel­er­ate and heads up to a par­tial vac­uum when you ease the throt­tle closed, thus us­ing less fuel. Em­ploy­ing cruise con­trol is best to main­tain a con­stant speed, which is good for con­sump­tion but, if you al­low the car to lose some speed up the hills and re­gain this with free down­hill momentum, you will save pre­cious- fuel.

4) AN­TIC­I­PA­TION

When­ever you use your brakes, you’re con­vert­ing fuel en­ergy into heat and all you gain from the en­ergy loss is com­ing to a halt. An­tic­i­pate hav­ing to slow down when ap­proach­ing traf­fic lights and stop streets. Main­tain­ing your speed and hav­ing to slam on the brakes not only wastes fuel, but wears out tyres, brake pads and discs/drums.

Al­ways keep your fo­cus on what is hap­pen­ing a few cars ahead. Is the traf­fic slow­ing? Is the next traf­fic light green? If so, chances are by the time you reach it, it will have changed to red. So don’t rush. If it is red, cruise slowly to­wards the lights in the hope that you can sail through as they turn green.

5) AIR DEN­SITY/ FRONTAL AREA

On the face of it, it would seem there’s noth­ing you can do about this. The larger the frontal area of your ve­hi­cle, the higher the drag and the more fuel you’ll use. It’s why an SUV uses more fuel than a small hatch. Did you know that, in Jo­han­nes­burg, you have less drag than at sea level since the air is “thin­ner”? Car de­sign­ers ob­vi­ously try to blend at­trac­tive shapes with prac­ti­cal low­drag aero­dy­nam­ics, but there are other ways you can com­pen­sate:

A RE­MOVE ROOF RACKS

It may look cool to have a surf­board or kayak on the roof but these play havoc with your drag fac­tor. Use them only when you are ac­tu­ally head­ing down to the wa­ter’s edge.

B RE­MOVE MUD FLAPS

Don’t, how­ever, do this if you of­ten drive on gravel roads or if you drive a bakkie or truck be­cause these are safety items pre­vent­ing stones and bricks from be­ing flung into the ve­hi­cle be­hind. Like­wise, don’t re­move your aero­dy­nam­i­cally in­ef­fi­cient wind­screen wipers (yes, some peo­ple ac­tu­ally do this).

C ADD A LOAD-BAY COVER

For the many bakkie driv­ers out there, con­sider ad­ding a canopy or load-bay cover. Ac­cord­ing to wind-tun­nel tests, a cover can re­duce drag by more than 5%. This could re­duce your fuel con­sump­tion by 1 to 2%.

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