Acceleration and Economy

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There is a great deal more to using a car's power than meets the eye. A car should not be driven hard or its performance abused, but power used wisely, in the right place at the right time, can be the safest course of action. When confronted with a hazard, it can be preferable to accelerate away rather than brake or steer your way out of trouble. Considering the efforts of car manufacturers to improve performance, and the importance which many car buyers attach to it, it is surprising how rarely this response is used by drivers. Moments do arise, such as during overtaking, when a car should be driven to the full extent of its potential, as more force with the right foot could keep a driver out of trouble rather than getting him into it.

Acceleration and overtaking

Unless you are travelling on a motorway or a dual carriageway, you have to move to the 'wrong' side of the road when you wish to overtake. This is an extremely dangerous place to be, and the longer you are there the longer you are exposed to the possibility of meeting oncoming traffic. It is absolutely essential to know exactly your car's acceleration potential, because you can find yourself in serious trouble if you expect more than it can give.

If you feel that you need to explore the capabilities of your car, find a deserted stretch of road with no low speed limits and put your car through its paces. If the car's instruments include a rev counter, use this to discover the maximum speeds possible in the lower gears; if there is no rev counter, the manufacturer's handbook will tell you the maximum speeds possible in each gear. Try a couple of runs to find out what the car can take so that you know how the engine sounds when it is close to its limit. You will probably be surprised just how much acceleration is available, even from a modest car, and it will give you a clear idea of what power to expect when you really need it.

You will normally not need to push the car to its maximum when you overtake, but you should still get by as quickly as seems safe and reasonable, from both your own point of view and that of the overtaken driver. Always select the right gear before starting to overtake. With a five-speed gearbox this is usually fourth or third, but second may be better if the vehicle ahead of you is travelling quite slowly (many cars can exceed 60mph in this gear). With a four-speed gearbox, third is the usual overtaking gear but many situations will demand second.

As you start the manoeuvre, apply the power smoothly; opening the throttle sharply is clumsy, and on a slippery road could cause the wheels to break traction (creating the wheelspin that can lead to a skid). It ought to be possible to complete the passing manoeuvre without changing up a gear until you have returned safely to the left-hand side of the road. If you do have to change up while you are overtaking, do so swiftly but smoothly, since releasing the clutch savagely can have the same effect as depressing the accelerator too suddenly.

Acceleration sense and economy

Acceleration sense must be acquired by every driver. This is the ability to judge, almost as second nature, whether you can safely carry out a manoeuvre and, having decided that you can, to make full use of your car's power while still driving safely. Acceleration sense comes only from experience and familiarity with the car you drive. Sensitivity in controlling the throttle is required to produce good acceleration sense, and for this reason you should always wear sensible shoes when driving. Many advanced drivers adopt the excellent habit of keeping a pair of thin-soled shoes in the car especially for driving so that they can exercise a delicate touch on the accelerator.

The way you drive has a dramatic effect on fuel economy, which is important to most of us. Without reducing journey times, an average motorist covering 12,000 miles annually could save as much as £100 a year on fuel by showing more sensitivity in his use of brake and accelerator pedals. Ramming the accelerator to the floor, revving too high and driving impatiently all use up fuel more quickly. Some drivers could also make a significant saving by abandoning the pointless habit of revving up the engine with the gearbox in neutral.

If road conditions are bad enough, harsh use of the accelerator can cause an accident. Most cars have sufficient power to spin the wheels if the road is wet enough. Even when moving off at traffic lights or from junctions, the combination of releasing the clutch too suddenly and applying too much pressure on the throttle can set the wheels spinning. The reaction of a front-wheel drive car will be a shudder, the noise of the engine racing and possibly some unnerving side-to-side tugging through the steering. A rear-wheel drive car can react more unpredictably, for wheelspin at the back can cause the car's tail end to start sliding round in a slow-motion skid which must be corrected with opposite lock steering. In all cars, whether the power goes through the front or rear wheels, your action should be to take your foot off the throttle and then re-apply power more gently.

Warming the engine

Before we leave the subject of acceleration, it should be mentioned that your car may respond less willingly before its engine has warmed up. Sudden opening of the throttle too soon after a cold start in the morning may cause the engine to falter, as if it is gasping for breath, or in an extreme case may even result in a stall. Having a manual choke on the wrong setting will make the engine even more sluggish. It is even more important than normal, therefore, to operate the accelerator progressively, and avoid demanding more from the engine than it is capable of giving. Be especially vigilant when pulling away from junctions and at roundabouts, especially if traffic is heavy. No car likes to be revved hard before its oil has had a chance to warm up, so let it reach running temperature in its own time.

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