Good: high quality, fast roof, fantastic dashboard

Not so good: high price, not very practical

Man, this car is fast. There's one stat you won't find in the tech specs that's arguably as important to owners of the new Audi TT Roadster as how quickly it accelerates from 0-100km/h. It's the amount of time it takes for the folding soft top to lower, or, crucially, rise back into place as the inevitable rain shower threatens to drown you and you passenger. Audi quotes just 10 seconds and it's tangibly fast. Like most decent cabriolets these days it's possible to open or close the roof on the move too - at speeds of up to 50km/h. Very handy in typical Irish weather.

Thankfully, the cabin of the TT Roadster is snug and dry with the roof up and your annoyance at the weather soon dissipates as you take in the marvel that is the Audi virtual dashboard. It's no different in the Roadster to that found in the TT Coupé, but it's a welcome refresher on how Audi is reinventing car interiors. It looks stunning, futuristic even, yet works intuitively and helps clean up the design of the rest of the dashboard. That's all well put together and made of high quality materials too and there isn't a duff control or switch in the car. The gorgeous leather and Alcantara upholstery is standard, with 'S line' embossing on this version, further emphasising the premium feel.

And at a starting price of €49,750 owners deserve to expect a premium experience. That's €2,200 more than the TT Coupé and the line-up mirrors that car's with a simple choice between two turbocharged 2.0-litre four-cylinder engines (leaving the TTS out of the equation). The petrol one is badged TFSI and produces 230hp; it is offered in manual or automatic (S tronic dual-clutch) guises with front-wheel drive or auto only with quattro four-wheel drive. The TDI diesel reviewed here is manual and front-wheel drive only. Trim levels are simply Sport and S line and in either the TT Roadster is well appointed. The TT Sport features Xenon headlights with LEDs for the rear lights and daytime running lamps; sports seats in leather and Alcantara; cruise control; a multi-function, flat-bottomed leather steering wheel; air conditioning (with switches directly on the air vents); 18-inch alloy wheels; the Virtual Cockpit dashboard and interface with MMI touch etc.; and Bluetooth telephony. Stump up an extra €3,500 for the S line model and the wheels are upgraded to a far sportier 19-inch design; sports suspension lowers the ride height by 10mm (it's a no-cost option); Audi drive select is added to allow the driver to select between various driving modes; the headlights become all-LED units and the rear LED indicators gain that 'sweeping' effect that really catches the eye; the wipers and lights are automatically activated; and last, but certainly not least, there's a visual makeover inside and out. We reckon it's well worth the premium.

It looks a million bucks in S line spec, but the spell is broken a tad when the TDI engine grumbles into life from cold. It's not a quiet unit. Thankfully it makes a good (if augmented) noise when on the move - sporty even - and its performance certainly lives up to the sharp promise of the TT's body. Petrolheads that like to rev an engine out to its last are better off with the TFSI petrol model, but everyone else will admire the effortless go on tap at seemingly any engine speed from this 2.0-litre TDI unit. Peak power of 184hp is not to be sniffed at, though the 380Nm of torque that's produced from just 1,750rpm gives this Roadster its personality.

That easy going nature means it's not difficult to maintain indecent progress across country when you're in a hurry, yet you won't have to keep stopping for fuel, as it's very economical. Audi quotes an official figure of 65.7mpg and most drivers will manage close to 50mpg. Some will wonder why those that can afford a €50,000 roadster worry about fuel economy, but it means less time wasted filling the thing up too. And of course the low emissions means a low road tax bill as well.

Saying all that, if you're trying to decide between the petrol and diesel versions of the Audi TT, we should be able to help. Do you love driving? Do you take the longer, more interesting road often? Do you take your car out to drive for the sake of driving? If the answer to all of these questions is 'yes', then you should stick with the petrol-powered model. It's faster, more exciting to drive and yet quieter around town. If you hesitated on some of those answers, or you need this purchase to fulfil the role of long-distance commuter, as well as a plaything for the weekend, then the diesel variant might be the sensible choice.

Thankfully, the TT Roadster drives fabulously regardless of what's under the bonnet. The steering is decently weighted, the manual gearchange smooth and quick and the pedal spacing and weighting are spot on. It's an engaging car to drive with rapid responses to input and a general feeling of togetherness in the corners. We would urge buyers to delete the no-cost sports suspension option on the S line version though, unless they live near a particularly well-paved set of roads. And if you do, can you please drop us a line and let us know where that is?

So are there no disadvantages to the new Audi TT Roadster? Well, the boot is 'bijou' and the looks won't be to all tastes. And then there's the Irish weather. Just as well it's so quick.