IF you ever wondered why someone buys a car like Audi's new 205mph R8 V10 tarmac scorcher here are two clues (and that faintly unreal top speed is a third).

Clue number one is a prominent button on the finely leather wrapped steering wheel; press it and the already fruity exhaust note turns so rudely vocal you can be heard in the next county. A bit anti-social and naughty... but nice.

You'll have to wait for darkness to appreciate clue number two, and be standing at the back of the car. Where you can see the engine in all its 10-cylinder glory, basking beneath a transparent cover and, extraordinarily, bathing in the glow of its own lights.

Then there's the paint choices, with many of the people ordering the first of the these new models going for vivid orange. Or red, or in semi-military matt green.

You will have gathered that the R8 is not a machine for shrinking violets. Or poor ones either, with a choice of two versions, starting at £119,500 for a car with 533 horsepower, up fifteen on the outgoing model and a tiny bit more economical too - although you'll be lucky to see 20 to the gallon in everyday use.

Pay a bit more (£134,500) and your car adds a 'plus' to its title and the 5.2 litres push out a deeply impressive 602 horsepower. That elevates top speed from a mere 198mph (hah!) to all of 205mph. The sizzle to sixty-two takes either 3.2 or 3.5 seconds and either will surely feel fast enough.

These performance figures put this most powerful ever road going Audi deep into exotic Lamborghini territory at a fraction of the price. But then they're both products of the VW empire and share very similar engines. You might say that makes the Audi a bit of a bargain; not a phrase you hear often.

Most of the early orders for the new A8 are for the dearer model which, like its less expensive sibling, is a little lighter than before and lower and wider, but shorter. A convertible model will follow in due course but there is no talk of smaller engines with fewer cylinders in the immediate future.

The added lightness is not down to paucity of equipment with the R8 which, as ever includes permanent four-wheel drive that turns the car into a properly practical all year round means of upmarket transport. There is even a modest boot at the front and enough space behind the seats for a briefcase and Gucci handbag.

Practicality moves sharply down the list of this car's attributes when you fire up the engine, especially from cold. The basso thunder will awaken the gods, and perhaps the neighbours too.

There is no option of a manual gearbox this time (a scant one per cent of owners previously opted for DIY gears) but the seven-speed manages things for you so convincingly you wonder why anyone might want to do it themselves.

Paddles behind the steering wheel let you attempt full-on Hamilton mode if the mood takes you, when the vast ceramic brakes of the R8 plus version will come in handy.

More surprising than the way the car goes and stops is the way it stays comfortable, certainly on the impeccable French roads of the car's press launch and hopefully on Blighty's more challenging surfaces.

No surprises that Audi tempts with a barrage of optional extras, from variable rate steering and adaptive suspension to extraordinary laser lights (at a neatly concise £3,000) and deeply sculpted seats, which proved less comfortable than the more adjustable standard versions.

Every new R8 has a big digital dashboard display which needed more study to fully fathom than a few hours at the wheel allowed. Also standard are sat nav and a cockpit swathed in lovely leather and as well applied as ever - Audi really do build cars that impress inwardly like no other at their price.

Impress outwardly too, especially if you like your car with an edge of restrained bling.