Feature: how to save fuel
CHANGING YOUR DRIVING STYLE AND SOME ASPECTS OF YOUR VEHICLE CAN GO A LONG WAY TO CUTTING COSTS
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.
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%.