Sometimes, for fun, bored men in their fifties go to something called High Performance Driving School. This is an OK thing for them to do, especially if it gets the ants out of their pants and keeps them from running off to Palm Beach for dirty weekends with 22-year-old swimsuit models. High Performance Driving School performs a valuable public service, really; it keeps marriages and reputations intact, even as it thrills and titillates and strokes the brittle middle-aged egos of its student drivers.

At High Performance Driving School, you learn how to gun the throttle of an expensive German car until the engine whines. You learn to "heel and toe" on the pedals. You learn to brake hard enough to give yourself a seatbelt bruise on your solar plexus, but lightly enough to avoid rolling your expensive German car or throwing it into a skid. You learn how to find the perfect line around every corner, and how to cut your speed at just the right instant, and how to know when it's time stomp back on the gas. You learn to feel the tires as extensions of your own feet.

After a weekend of that, should fate bring you and Gran Turismo 4 together, you will all but drown in your own endorphins.

For everyone who has not recently been to High Performance Driving School, mind you, the game is a bit of a drag. Here is how it works.

First, someone gives you 10,000 of something called "credits," which you can use to buy cars and automotive accessories. Prices are not always fair, and sometimes an underpowered high-mileage Honda rumpmobile from the 1980s will cost far more than it has any business costing, but most of the time one credit is roughly worth one euro. Your goal as you play the game is to win races and collect prize money, which you then use to buy bigger and faster cars, which you then use to win bigger and faster races, which offer fatter purses. Repeat repeat repeat and soon you have an enormous collection of new and vintage cars.

Er, that's it. The point of the game is not to win so much as it is to collect. Every race comes pre-packed with a leaderboard of outstanding lap times to beat, and every one of these offers a cash prize. Sometimes winning a race unlocks new tracks for you to drive your cars on. Sometimes it even earns you a new car for your collection. On every track and in every race, there is incentive to try again, nudging your finish time downward by a few hundredths of a second in the hope of adding another Citröen to your garage.

To participate in any but the easiest races you must first earn a licence. You do this by completing a series of blisteringly dull exercises in acceleration, braking and cornering. Every licence comes in three levels: bronze, silver, and gold. Each level comes with a prize. Nerdy completionists will love it.

How are the races? They are true to life. If you take a corner too fast you will have trouble steering. If you hit the gas too hard at the wrong time you will spin out and finish last. The races encourage safe driving habits and punish wantonness.

Everywhere you go, real-world physics follows you, wagging its finger and telling you to keep your id in check and your impulses under control, lest you run off the road and dust up your car. Stick to the straight and narrow, the physics says, or you will pop your bubble and miss all the wholesome fun.

No question, this is all terribly healthy for society at large, just like High Performance Driving School is. Oh, for some giddy irresponsibility.