When you buy a washing machine, does it ever cross your mind that the water could be injected into the drum a little more quickly, or that the spin cycle could be turbocharged in some way? No? Well what about your lawn mower? Ever thought of chrome plating the blades or supercharging the two-stroke? Really? You’ve never felt the need to fit blue underfloor running lights or add a whale-tale spoiler? Of course not, and rightly so. There is a very good reason why you leave your household goods alone; because you have a sense that they’ve been designed to be as good as possible, and that if you start tinkering you’re going to make them worse.

I bet, therefore, that your toasted sandwich maker is exactly as it was when it came from the shop — still in its box, even. And I’m also willing to bet that you have not modified your car in any way, either.

Obviously this doesn’t apply in America, because any nation that can’t make a cup of coffee and is utterly confused by the recipe for “a pot of tea” is going to struggle pretty badly when it comes to something as complex as making a car.

So if you have a Buick or a Chevrolet, then even a four-year-old child with a Fisher-Price screwdriver set could make dramatic improvements. If you have a Pontiac Aztec, you may as well wheel it to a spot under your kitchen worktop and attach it to the plumbing, because it would make a better washing machine than it does a car.

That’s why America is awash with small tuning companies to whom all car enthusiasts turn when they’ve bought a car from GM, Ford or Chrysler.

What’s more, Americans always think they can do better. It’s why they try to tune and customise shows like The Office instead of just buying ours.

Here in Europe, however, things are different. Yes, there are tuning companies — Overfinch for example — who do good work. But as a general rule we steer clear of trying to make improvements because we have a sense that when it comes to the business of making cars the car makers are better qualified than some bloke who rents an arch from Network Rail.

I looked at a new Jaguar XK8 last week that had been modified by a company called Racing Green. It looked tremendous and the performance figures were impressive too. But I noted the enormous wheels and the low-profile tyres and couldn’t help thinking: “If they work, then why didn’t Jaguar fit them in the first place?” More worrying are those who try to change a car’s performance using nothing but a laptop.

You may not know this but the engine in your car, providing it isn’t a Riley or something else from the days when black people were funny, is controlled by a computer with simply awesome power.

It reads the humidity, checks the weather and notes the ambient temperature. It sees where you have your foot on the throttle, what gear you’re in, whether you’re going up a hill or down the other side, and when it has all the information it needs it refers to a “map” and thinks “Okay. If it’s this hot, and the car is in this gear, and the throttle is in this position, the ‘map’ says I must inject precisely — to the nearest atom — this much fuel into the cylinder”.

And if you have a four-cylinder engine turning at 4000rpm the computer is referring to the map and making these infinitesimal decisions 133 times a second.

The map is drawn by clever people who live with their mothers and do not know what daylight looks like. It is designed so that the engine uses the smallest amount of fuel while providing the cleanest possible exhaust and the maximum amount of power.

The map, then, is a series of compromises and if you, too, are the sort of person who lives in the dark and likes to hack into defence computers and start world war three, you can access it with a simple laptop and make changes.

Great. But it doesn’t always work. Recently, at the MPH show in Earls Court, we needed to change the handling characteristics of the new Jaguar XKR. On the slippery floor there was too much understeer and any attempt to kick the rear end out with a bootfull of throttle resulted in one rear wheel spinning uselessly.

Naturally I suggested hitting it with a hammer, but no. A man plugged a laptop into the car’s computer and with each strike of the keyboard he made the handling just a little bit worse. Each time he made alterations to the map, trying to improve one thing, something else would cease to exist altogether.

I’ve seen this before, at various Formula One races, and when very high performance cars are delivered to the Top Gear test track. People in corporate short-sleeved shirts try to cure misfires, and a million other maladies besides, by plugging the car into a laptop and giving the map a new set of compromises. It never works. Ever.

The misfire may be cured but the downside is that when you start the engine it immediately sucks all of the sky into its cylinders and then bursts. Or it shoots so much carbon dioxide out of the back that the temperature shoots up to a million and we all die.

I’m not saying that car companies always get it right. They don’t. But they’re more likely to get it right than you. And that brings me on to the Volkswagen Polo GTI.

This comes with a 148bhp version of the turbocharged 1.8 litre 20-valve engine that produced 237bhp in the old Audi TT. So why not simply change the map and, hey presto, you have a 237bhp Polo. Wow. With something like that, you could bend time.

Hmm. I advise caution, because while the engine is certainly strong enough to handle 237bhp, the car isn’t; something you will discover about half a second before you hit the tree.

If Volkswagen thought that the Polo could handle 237bhp, then it would have 237bhp. They’ve decided that 148bhp is about right, and I agree.

In many ways this little car is the spiritual successor to the original Golf GTI. Back in 1981 that cost £5,700, which in today’s money is around £13,000 — £7,000 less than the current, much bigger Golf GTI.

The Polo is not only closer in size to the original hot Golf but at £14,810 closer in price too.

And spirit. It has few of the fancy add-ons that have all but killed off the hot hatch as a volume seller these days. Apart from a lower ride height, and a honeycomb grille, it just looks like a small car that happens to have a big engine. And I like that.

I liked the handling, too, the sense that you can go round any corner at any speed. And I liked the power. Yes, there’s a bit of turbo lag, but if you stir away at the gearbox that’s eliminated and you’re left with a little car that’s genuinely nice to drive.

It’s also surprisingly practical, well equipped and easy to park. And it’s easy to mend, because of course the wing on a Polo GTI is exactly the same as the wing on a normal Polo.

The only problem is that if I wanted a fun little car I’d rather have a Mini — a car where you really can save money and get better performance with a bit of after-market tuning.

An £11,000 Mini One does 0 to 60 in 11 seconds and has a top speed of 112mph. A Mini Cooper, with exactly the same engine, does 0 to 60 in 9 seconds and has a top speed of 126. How? Simple. The “map” is different.

So instead of buying a £13,000 Mini Cooper, go for an £11,000 Mini One — which is exactly the same — and then pay someone with an Oedipus complex a hundred quid or so to change the map.

I hope that, for once, I’ve been of some use this morning.

Vital statistics

Model Volkswagen Polo 1.8 GTI
Engine 1781cc, four cylinders
Power 148bhp @ 5800rpm
Torque 162 lb ft @ 1950rpm
Transmission Five-speed manual
Fuel 35.8mpg (combined)
CO2 190g/km
Acceleration 0-62mph: 8.2sec
Top speed 134mph
Price £14,810
Rating 4/5
Verdict The new Golf GTI, but that said, I’d still prefer a Mini

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