Technical Skills


Ever pressed hard on the brake pedal to reduce speed and felt a grating, vibrating sensation through your right foot. There is no fault with the brakes! Chances are you’ve activated the ABS, which you’ve seen on car ads and on the car dashboard when starting up and wondered what it was all about.

ABS detects when any one or more wheels (i.e. tyres) is about to skid under braking and is activated to put the brakes on and off up to 20 times a second (hence the grating feeling). Speed is reduced but ABS allows the wheels to continue to rotate. So what does that enable the driver to do?

Imagine braking hard and skidding. Without ABS, the wheels would ‘lock up’ and the car ‘plough on’ in a straight line! Turning the steering wheel will make no difference to your direction whatsoever. With ABS, the wheels are allowed to rotate under braking, allowing you to emergency brake and steer. Want an easy way to remember the main benefit: ABS, A llows B raking and S teering.

So do ABS brakes shorten stopping distances? NO! They don’t. Think about how they work again. ABS puts the brakes on and off up to 20 times a second. So the brakes are on 50% of the time and off 50%. If you release a little brake pedal pressure to just de-activate ABS, creating 100% braking effect but less hard, you will brake in a shorter distance.

If you are braking under ABS in an emergency, look for the ‘escape’ space to steer towards and don’t look at whatever caused the problem. You will always steer towards what you are looking at!!This text block can be expanded.

Changing Gear
Nothing to do with wearing a new outfit or exchanging illegal substances!!

Have you ever seen TV film reports on driving through towns and, when interviewed, the driver of a prestige, performance car says to the reporter, “This car won’t do 30mph!!”.

The car’s top speed is probably 4 or 5 times that so it’s not the driver complaining that the car is too slow. The problem is that he or she is trying to drive at 30mph in 4th, 5th or 6th gear and the speed is difficult to control. Selecting no higher than 3rd gear would give a lot more urban speed control, give more ‘flexibility’ with improved engine braking when decelerating and eliminate excessive braking and gear changing when negotiating hazards in towns.

“But my driving instructor told me to get into ‘top’ gear as soon as possible and my dad says ‘top’ saves fuel!”. Firstly, when you learnt to drive in a Nissan Micra 1.0L 4 speed gearbox, or something similar, 4th gear may well have been a much lower gear ratio than 3rd in most medium powered, 5 speed production cars.

Secondly, selecting no higher than 3rd gear in 30mph limits does NOT use more fuel. Fuel consumption is not governed by the speed of the engine but by the position of the accelerator pedal. Pressing the accelerator down in too high a gear squirts excessive fuel into the engine and becomes ‘unburnt’. If you are fortunate to drive a vehicle with an instantaneous fuel consumption read-out, try it and watch the mpg drop dramatically.

Smooth gear changing up or down can be measured by what I term the ‘passenger test’. Does your passenger ‘bob’ noticeably forwards and backwards every time you change gear? When you accelerate, due to weight shift, the front of the car goes up and the back goes down. On changing gear, power to the wheels is momentarily removed then replaced and the car ‘rocks’ on it’s suspension. Try settling, balancing or ‘plateauing’ the power just prior to changing into each higher gear and you’ll find that your passenger acts less like a ‘nodding donkey’ and may well praise you for a ‘chauffeur-like drive!’.

So, use gears intelligently to improve driving and manage speed more effectively. Try this:-
No higher than 2nd gear in 20 mph limits
No higher than 3rd gear in 30 mph limits
No higher than 4th gear in 40 mph limits
and you may well keep a few penalty points off your driving licence!

For those of us who are into TLAs (Three Letter Abbreviations), BHP means Brake Horse Power. Simply put, this is the maximum power delivered by an engine at a particular engine speed, denoted in RPM (Revolutions Per Minute). Also, if you ever see max. power output is, say, 150PS, and you did GCSE German, PS means Pferde Starke, Horse Power auf Deutsch, sorry, in German. So it’s the same thing!

Due to rapid developments in engine design technology, the choice between buying a petrol or diesel powered car is becoming more difficult. Modern diesel powered cars are clean and can deliver amazing performance. Remember the Astra GTE 2.0 litre 16 valve? In the early 1990s its petrol engine was used in the Formula Vauxhall Lotus race series. Today you can buy a VW Golf 2.0 litre TDI (Turbo Diesel Injection) with the same power output! Not only that, but a colleague of mine who runs one of these is getting 65 – 70 miles per gallon, and he used to race Stock Cars!

Diesel powered cars can cost more to buy and may require more frequent engine oil and filter changes than petrol cars. However, from a taxation viewpoint, modern diesel engine emissions are low, providing significant benefits to the personal allowances of company car drivers. Diesel engines are not only very reliable (no spark plugs or electrical ignition timing involved) but they also last a long time – see how old some of your local diesel powered buses are.

So, look out for performance cars like the BMW 330d (this is the one Jenson Button got stopped doing 140+mph in!) and stylish cars like the Peugeot 406 Coupe diesel. I make no excuses if I come across as a bit of a diesel fan. Well actually I’m not! I am a BIG fan! Who knows, in the next five years I might be writing about the new Ferrari Diesel! Now that would be something!

Finally, I hope this doesn’t make you despair about UK fuel taxation, but do you know the cost per litre of diesel fuel in Cyprus? 18.1 pence!! (BBC2 CEEFAX P497).

Exhaust Emissions
In the ‘Old Days’ (1950’s) places like London often suffered from, given particular circumstances, a choking atmosphere called SMOG (SMoke and fOG). This was witnessed in other European cities. Across the Atlantic, a ‘heat haze’ of sunshine refracting through a deep layer of car exhaust fumes often blanketed American cities. Respective populations had no choice but to breathe this unpleasant air. Something had to be done!

‘Smokeless zones’ were brought in to legally regulate smoke levels from home fires and factory chimneys and for cars, similar laws began a technological revolution in engine efficiency and reduction in emissions of harmful exhaust gases.

OK, I am going to have to go a bit technical now but I’ll try to keep it simple!

The main emissions of a car engine are:-
Nitrogen gas – air is 78% Nitrogen so most passes straight through the engine.
Carbon Dioxide – a product of combustion.
Water vapour – another product of combustion.

These emissions are mostly harmless, although Carbon Dioxide is believed to contribute to global warming. Because the car engine combustion process is never perfect, some smaller amounts of more harmful emissions are also produced.

So what is a Catalytic Converter? This is a device that uses a catalyst to convert three harmful compounds in car exhaust into harmless compounds.

Wheels and Tyres
Big and important topic, this one! Look at the palm of your hand. Not that big is it? But that’s the size of the ‘contact patch’ between each properly inflated tyre and the road. Unless you’re on a motorbike, or driving a Reliant Robin, you have got four of these helping you brake and corner.

When manufacturers develop cars, a lot of research and testing time goes into correct types and sizes of wheels and tyres to give optimum performance, at correct tyre pressures, under braking, cornering and accelerating. But you’ve just looked in the local motor discount shop and seen a superb looking set of wide alloy wheels that will impress your mates and help you look cool for the girls! Take great care! Unless wheels and tyres are approved for your car, you may end up with less grip than you started with!

It’s time for a quick Q&A test on tyres. Here goes:-
1) What is the legal minimum tyre tread depth in the UK?
2) Who is legally responsible for tyres, driver or owner?
3) What is the maximum fine per illegal tyre, in points and money?
4) How often should we check tyre condition and pressures?
5) Why is it that screw or nail punctures happen

1) 1.6mm, across the central 3/4 of the tread and all the way round.
2) Always the driver, with possible incrimination of the owner.
3) 3 penalty points and up to £2,500 per illegal tyre!
4) Weekly minimum, but check before driving after someone else has –
they may have ‘kerbed’ the front, nearside tyre and damaged it!
5) The front tyre runs over the screw or nail, flicks it upright and the rear tyre runs onto it!

In the wet, incorrect tyre pressures and shallow tread depth reduce tyre performance dramatically!! Please Check Your Tyres Often!!

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Driving Skills for Life