To sum up cruise control in one sentence, you would say this - it maintains a speed you've set for your car, without you having to keep your foot on the accelerator.

It may come as a surprise then, that a blind man called Ralph Teetor invented the first cruise control for cars in 1945. As my old, senile, arrogant History teacher used to tell me: "necessity is the mother of invention". For a change, he was right. Mr. Teetor was really frustrated with the way every time he rode in a car with his lawyer, the car would never seem to keep a constant speed.

So anyway, the system itself. Cruise control is most common in American cars, where long straight interstate highways are typical drives, but in European cars it is also quite readily seen, since they have lots of Autobahn-like roadways spanning the continent. In Japanese cars it used to be quite rare, since Japan lacks roads like the ones mentioned above, but Japan are increasingly producing cars for world tastes, and nowadays cruise control can be found just about anywhere. It's great if you do a fair amount of freeway driving, where you don't want to accidentally go over the speed limit and get a ticket, or tire yourself out to much on a long drive. Studies have shown that using cruise control can also lower the fuel consumption of most drivers.

So the example I've used to show you how it works is a Chrysler from the late nineties - primarily because it's designed for Americans, so it isn't too confusing for their questionably sized minds. But really, it was the easiest to explain. Cruise control systems don't look the same on every car. Some cars have buttons attached to the steering wheel, like this one, or buttons actually on the steering wheel , or a stalk protruding from the steering column, like the stalk to operate your windscreen wipers. Different brands do it different ways. But they all have similar functions, and the same basic ideas.This example has on/off buttons, which not all cruise control systems have, since they are rather superfluous. Hitting the "on" button doesn't actually do anything, other than tell the car that you might be pressing another button soon, so those buttons are then activated. The "off" button disables the cruise control, meaning you have to once again control the speed of the car with the throttle (which is a fancy name for the accelerator, if you're wondering). But the thing is, not all cruise control cars will have this button, because touching the brakes (or the clutch too if you're in a manual) will automatically disable the cruise control. Nifty, huh? So if you're on the freeway cruising at 95, and suddenly need to slam on the brakes, you can do so without the car accelerating against you. So you can see why some cars don't have these on/off buttons, because their not really needed.

The "set/accel" button is the one that actually sets the cruise control to work. Whatever speed you're doing at the time you press this button, the cruise control will then maintain, so you can take your foot off the accelerator. So say for example you've just set your speed to 95. But now you want to accelerate to 100 - all you have to do is tap this same button five times, and it will increase your speed by five kilometres per hour. Some poorly coverted cars may still operate in miles per hour, so if you press this button five times, it will increase your speed by five miles per hour instead, which is like eight kilometres per hour, so be careful!

Holding down the "coast" button is exactly the same as what would happen to the car if you took your foot off the accelerator normally - it allows the car to roll, or "coasts". But say for example, we've had enough of cruising at 100 kmh, and wanted to get back to 95 - all we'd have to do is tap this button five times. So it works exactly the same as the "set/accel" button. Simple, right?

Except, like I said earlier, not all cars will be set up like this one - for example, there might just be a set buton, and a coast button, and then two other buttons, one with a "+" , the other with a "-". But it surely doesn't take a genius to work out what they do - it may look different, but it will have the same functions.

Oh, I almost forgot - the button that says "resume" is a handy little feature, too. If you've recently braked, and thus disengaged the cruise control, pressing this button will take you back to your last set speed. Easy.

Right, but I do have to say - you can't use cruise control at just any old speed. The minimum speed for a cruise control to activate is different, depending on the car, but usually it is somewhere between 40-60 kmh. It's so that you don't use it while you're driving in suburban streets, where the traffic is more variable than for instance, a freeway.

I don't think anyone really wants to know how it works - it's complicated... - but if one of your friends asks you about it, and you want to look smart, mumble something nerdy and throw in the term "vacuum actuator", 'cause that should do the trick nicely.

These days, as technology grows, premium brands like Mercedes-Benz have developed even better forms of cruise control - called "adaptive cruise control". It's so called because it uses a radar to adapt the speed of your car to maintain a safe distance between you and the car in front. So if the car in front of you slows down, the cruise control will automatically slow down to match them, leaving you enough space if you ever need to brake suddenly. No button tapping required. It's pretty fancy, isn't normally a feature on everyday cars, and can get rather wierd when your car comes up with a display that can measure the distance between you and the car in front while you're driving (like this Mercedes-Benz S-Class, which debuted some of this technology back in 1999). Yes, I know it's nuts.So that's cruise control. I know that was a long explanation, but it seems that no-one is willing to thoroughly explain it - probably because they assume it's common knowledge. But I think the truth is that quite a lot of drivers who have cars with cruise control don't know how to use it effectively, or are confused by all the buttons, or simply dismiss it as a lazy way of driving. This, of course, is silly, because you've probably realised by now that cruise control has a lot of merit. At least you know all about it, now.

LINGO: Cruise Control