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Are you one of those drivers who likes to play the motoring equivalent of Russian Roulette with your car’s fuel gauge? If so, you are far from alone.
It emerged yesterday that every year 827,000 of us ignore the helpful glow of the warning light, run out of fuel and — surprise, surprise — break down.
A survey carried out by an insurance firm revealed that a quarter of drivers believe they can eke out at least another 40 miles when the light is showing. Two million drivers even admitted to driving with the warning light on almost permanently, mainly in the hope of finding cheaper fuel.
Men are the biggest culprits, on average tending to believe that the car still has enough fuel for another 32 miles.
Women, more cautious, suspect the engine will conk out after 24 miles. As a result, six out of ten drivers who run out are from the more optimistic (make that ‘more foolish’) sex.
Running out of fuel is no laughing matter and can be far more serious than having to make either a sheepish call to the AA or a lonely trudge to the petrol station where you will be fleeced for a Jerry can. You are risking costly damage to your car, as well as putting yourself in danger.
In fact, the driving test should arguably involve being quizzed on the perils of running out of petrol rather than being made to reverse around a corner: under-35s were revealed as making up two-thirds of the drivers you will see standing glum, and vulnerable, by the roadside having exhausted their petrol.
So what are the risks and if you are a long way from a forecourt, what is the best way to conserve the last drops? The first thing to realise is that fuel gauges are not precise instruments. Even in the most modern and snazzy cars, the technology is relatively basic: the level in the tank is measured by a float, like the ballcock in a lavatory cistern.
The height of this float is then relayed to your gauge either electronically, or through the use of metallic strips and coils.
It explains why the level of petrol in your tank can fall or rise depending if your car is on a gradient. And it means that when your car tells you how many miles you have left in the tank, or that you are about to run out, it can only ever be a rough guide.
Fuel gauges are not precise instruments – even in the most modern cars, the technology is relatively basic: the level in the tank is measured by a float, like the ballcock in a lavatory cistern, and are only ever a rough guide
To add to the uncertainty, the distance that a car can travel after that light first pops up varies wildly. A Mercedes C-Class, for example, can cruise along for an average of 46 miles, whereas a Vauxhall Astra will more likely give up at 26 miles.
So it’s best to head straight to the nearest pump. If you don’t, because you are trying to nurse the car back to that garage near home where fuel costs a whole 2p less per litre, bear this in mind: exhausting your petrol can cause a lot of damage to your car and your wallet. Diesel drivers face an even higher bill.
‘Running out can cause a lot more damage to diesel engines,’ says Ray Sparrow, a mechanic for nearly 40 years whose garage, Autowork, is in Salisbury, Wiltshire. ‘The bills can run into thousands. That may be good news for a garage, not for the driver.’
Without getting too technical, the seals, pumps and injectors in a diesel engine can be damaged by the engine drawing just on air, rather than a rich, oily mix of diesel and lubricant. ‘You may just get away with it,’ says Mr Sparrow, ‘but you’ll be causing expensive problems down the line.’
Petrol engines fare a little better running on empty, and are less likely to suffer severe damage. But there is little to be complacent about — even if you do have petrol in the boot, or get some from a garage, you may find the car still won’t start.
The likelihood is that air will have built up in the system, stopping the fuel moving from tank to engine and, in that case, you will need a mechanic to ‘bleed’ the system, much as one has to bleed a malfunctioning radiator at home. The net result is that you’re not going anywhere fast.
Also, by relying on fuel from the bottom of a petrol tank, you risk clogging up your filters and pumps with sediment. ‘Think of it as the bottom 10 per cent of a bottle of decent red wine,’ says Mr Sparrow. ‘It’s not the stuff you want to drink, is it?’
Modern cars will suffer worse than a jalopy. As Mr Sparrow says, newer car systems are more sensitive and the tolerances much tighter.
There is a further chapter in this cautionary tale: the temporary effect, when the engine stops, on power steering and brakes. Neither works as you are used to, which makes pulling over more difficult. ‘The brakes will require a lot more pressure and the steering wheel will be like a massive heavy wrench,’ says Mr Sparrow. His advice is to drive around with a minimum of a quarter of a tank of fuel: ‘There’s no point in saving £20 today, to have to spend £2,000 tomorrow.’
This is what to do if you still find yourself running on vapour.
Try to drive as ‘fuel-efficiently’ as possible. Maintain an even speed of around 40-50 mph if it’s legal, and avoid sudden braking and acceleration. Look at your rev counter, and try to pick a gear that keeps the engine running between 2,000 and 3,000 rpm.
Don’t be tempted to freewheel; you can’t accelerate and could end up with points on your licence if caught by the police for not being in control of your vehicle. Moreover, most modern cars use less fuel when they are in gear as long as the accelerator is not depressed. This is because when you put the car into neutral, it will go into ‘tick-over’ mode (as if you were idling at some traffic lights), which uses more fuel.
Turning the car off when stationary will save fuel but only if you stop for more than a minute. Starting a car uses the equivalent of about a minute’s worth of fuel with the engine at 2,500 revs.
Best of all, remember the Jerry can. Those spare five litres may not only save your face, but also the cost of your next holiday.
Read more: http://www.dailymail.co.uk/news/article-3213671/Why-never-drive-quarter-tank-fuel-827-000-break-year-ignoring-warning-light.html#ixzz3sywSbAaY
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