CAREERING around the Cotswolds with a lunatic grin on your face is likely to get you pulled in, even if you are speed-legal.

Best not raise suspicion then and adopt a more sombre expression. But that proved difficult taking the all-new Audi TT Roadster for a spin.

Even my co-driver looked as though he'd had a whiff of laughing gas - and that's before he got behind the wheel.Perhaps "spin" was stretching things a little.

There was no handy race circuit but we did manage to open up the cars on some decent A and B straights as well as manage several blastings on the motorway for some force-fed fun and oxygen.

The TT proved an immediate trendsetter when it made its debut in the late Nineties. It was daringly different and despite the changes since 1999, it remains as distinct and stunning as ever in its third generation presentation.

Fine sculpturing and endless wind-tunnelling have whittled down aerodynamics to class-leading figures resulting in a slightly edgier silhouette. It has been accomplished without the designers over-tinkering with that still wonderfully smooth and unmistakable TT shape which retains the seductive contours of the original car.

Back in the Nineties, the car's driving dynamics were adequate rather than rivetting. The car's looks did the talking.

Today, it's a different story. Image still plays a massive part in this sector, but performance is hugely important, too.

The ‘Sweet Sixteen' year-old TT has matured into a much more serious contender in the performance stakes, with both the soft-top and hard-top benefiting from new efficient, high-performance engines, new platforms, chassis and body.

It translates to power output increases varying from eight to nine per cent over previous models while the improvement has been nearer 14 per cent for the TTS model.

This, in turn, has raised the Roadster and Coupe's sprint times to equate and in some cases surpass that of competitors in the hot, premium sports car sector such as the BMW Z4 sDrive35i M Sport, Mercedes-Benz SLK 350 AMG Sport automatic and the Porsche Boxster S.

The 2.0-litre (230PS) TFSI quattro S line S tronic Roadster can pip the Porsche Boxster PDK to the 0-62mph post, albeit by a whisper (5.6 seconds against the Porsche's 5.7 seconds).

Again, the TT (310PS) Roadster quattro S Tronic registers 4.9 seconds against the Porsche's 5 seconds, while the TTS quattro S tronic Coupe takes 4.6 seconds against the Porsche Cayman PDK's 5.6 seconds.

At the same time, C02 emissions have been whittled down by between 11 and 16 per cent across the range with the exception of the 2-0-litre TDI diesel unit which boasts a significant 26 per cent reduction in emissions over the previous engine, with a similar percentage improvement in mpg returns.

These achievements may not excite but are important and form part of Audi's long-term goal for C02 neutral mobility.

The newly-launched TT Roadster follows closely on the unveiling of the hard top sibling. They come in three engines sizes in total - the 2.0-litre (230PS) and 2.0-litre (310PS) petrol units and the 2.0-litre (184PS) diesel engine which boasts an impresssive average fuel consumption of 65mpg. They are offered in conjunction with front-wheel-drive and quattro all-wheel-drive transmissions, though the 2.0-litre 184PS diesel comes exclusively in two-wheel-drive.

There are two specification options - Sport and S line - all including the automatic, three-layer acoustic hood, digital Audi virtual cockpit, MMI touch, xenon or LED headlights, Audi Music Interface, Audi drive select, Alcantara-leather sports seats and keyless go.

The S line models upgrade to larger 19-inch alloys, all-weather LED headlights and LED tail lights flanked by rear indicators with a directional sweeping function, S line body styling with all models fitted with a spoiler that is electrically extended from the luggage compartment lid at speeds of up to 74mph, providing extra downforce.

First UK deliveries for the open-air TT are now under way with the potent TTS Roadster arriving in June.

Prices range from £31,955 to £37,555 and climb to £42,455 for the TTS 310PS quattro with S tronic gearbox.

We set off for a two-hour taster in the 2.0 TSI Roadster S line with 230PS output and a six-speed manual gearbox (Audi forecast 70 per cent of sales will be taken by S line models), and even without the quattro elements it felt supremely planted, poised - and fast - with amazing, progressive grip.

The hi-tech fabric hood was already stored in its bespoke aluminium tray, with the wind deflector employed at the touch of a button and doing exactly what it says, though not diminishing too much the wind-in-the-hair experience.

At the same time, it exhaled warm air at neck level while the heated sports seats kept driver and navigator nicely toasted. This, despite sunny but low temperatures.

Who cares, we chimed? We were snug enough in a lavishly-tailored interior with the accent firmly on the Q for quality factor.The dashboard is quite amazing with Audi's virtual command area almost entirely enveloped into a 12.3-inch hi-res LCD display screen, taking over the driver's binnacle.

It can juggle from 'classic view' with speedometer/rev counter information and such but switch to "infotainment" where the read-outs are made smaller to make room for other functions, like the navigation map. It is a little overwhelming at first, but practice soon makes for ease and intuitive use.

We, and the 155-mph Roadster, finally succumbed to a cloud burst, employing the acoustic hood in its claimed time of 10 seconds.

On this occasion, we had sufficient time and convenience to pull in and complete the exercise in 'park', but it actually can be achieved at up to speeds of 31mph.

With such panderings and molly-coddling to occupants - and with such a rapid cover-up time - may be the new TT Roadster should be billed the new, all-weather performance soft-top that ignores whatever the British weather throws at it.