You don’t have to travel an inch in this new Audi TT RS to discover its appeal. You don’t have to gaze at its pumped-up shape nor look at its substantial rear wing or new braking system and wonder what kind of power it must have to control.

All you need to do is listen. And then you will hear, in one blip of its throttle, why people will buy this car. It’s a noise no Audi has made for more than a decade and one many had feared had gone for good; but now it’s back it already seems hard to believe it ever went away.

The sound? The unique offbeat thrum of an Audi five-cylinder turbo motor, immortalised for all time by Detective Chief Inspector Gene Hunt’s wheels of choice, the legendary Audi quattro.

It’s been 32 years since Audi became the first mainstream car manufacturer to put a five-cylinder petrol engine into series production, and 15 years since, unable to keep up with emissions legislation, it was sadly phased out. In that time the engine helped win innumerable rallies, powered successful racing cars and set Audi on the road from being a note in the margin of the German car industry to the main player it is today.

The reason it’s back beneath the bonnet of the TT RS is not quite as romantic as it may at first appear — Audi wanted an engine with about 340bhp so it could outpower the 320bhp Porsche Cayman S and the only one in the stable was the 3-litre supercharged motor in the S4 — and that didn’t fit.

The answer lay not in another Audi, but a Volkswagen — a Jetta that’s sold only in America. It had a 2.5-litre capacity and Audi realised that not only would it fit the TT but if a turbo were added, the required output could easily be reached. Despite what you may read elsewhere, what this engine emphatically is not is one half of the 5-litre V10 engine used by the Audi RS6.

Despite the engine’s humble origins, there is nothing in the least bit wrong with what it delivers. Indeed, and thanks only in part to the traction advantage of its Haldex all-wheel-drive system, the TT RS will catapult to 62mph in just 4.6sec, faster than the Cayman S, Mercedes SLK 55 AMG, BMW Z4 sDrive 35i and any other car that might describe itself as a rival.

Its top speed is limited to 155mph, unless you give Audi a further £1,300 in exchange for which it will give you some carbon-fibre trim and a derestricted engine that will run all the way to 174mph, which, again, is more than any of its principal rivals can manage.

Even so, it is the haunting note of the engine as its sears its way to the 7000rpm red line that is likely to live on in your mind long after the memory of its bald performance has faded. Porsche, BMW and Mercedes may provide more cylinders than this, but so far as the soundtrack is concerned, Audi has them all licked.

However, it takes more than a big engine to turn any Audi into an RS model and Audi’s quattro GmbH division (which is to Audi what AMG is to Mercedes) has been through the TT from end to end to ensure it’s worthy of this startling new engine.

At the front the air intakes have grown, while at the back there is a new, larger and fixed rear spoiler in place of the smaller, deployable item of the standard car. There is also a diffuser panel beneath the rear bumper. At the side you’ll spot the pumped-up skirts and new, very smart 18in wheel rims.

Inside you’ll find bespoke bucket seats complete with TT RS logos, a flat-bottomed steering wheel, matt black and polished aluminium trim and, if you know where to look, a special function in the trip computer providing information on oil temperature, turbo-boost pressure and, should you be on a track, even your lap time.

What you can’t see is that a new six-speed gearbox has been fitted with ultra-short throws to add further to its sporting appeal, although anyone hoping for a DSG-type paddle-shift transmission will be disappointed: the official line is that the TT RS is so sporting, customers will want to change gear for themselves.

That may or may not be the case but what is true is that Audi does not have a DSG gearbox that will fit under the TT’s bonnet and handle the torque of the RS engine.

The package is rounded off by special sports suspension with the option of electronically adjustable dampers and a set of impressively vast brakes to make sure that however quickly it may accrue speed, its ability to lose it is more impressive still.

I drove it on the road but, informatively, also on the Zolder racetrack, a tricky and technical circuit even when it’s not pouring with rain. Which it was. In those conditions the TT RS was everything you might imagine a high-performance Audi to be: effortlessly fast with foolproof manners offering a stability even under the most unreasonable provocation, making it by far the easiest car in its class to drive in such circumstances.

A Porsche Cayman S offers a considerably more rewarding drive but if it’s maximum speed for minimum effort that interests, this car is for you.

Sales of the TT RS start next month, with the coupé version costing £42,985 and the slower, uglier and less rewarding roadster priced at £44,885. Audi says it will bring only 200 to the UK this year so if you want one, I wouldn’t hang about.

Recession or not, however fast the TT RS may move down the road is likely to be as nothing compared with the speed at which it will move out of the showroom.

Hot Wheels specs

Engine type 2480cc, five cylinders in line

Power/Torque 340bhp @ 6300rpm/ 332 lb ft @ 1600rpm

Transmission Six-speed manual

Fuel/CO2 31mpg (combined) / 214g/km

Acceleration 0-62mph: 4.6sec

Top speed 155mph

Price £42,985

Road tax band K (£215 for a year)

Verdict Worth it for the sound alone

On sale June 2009