With the new A3 Cabriolet, Audi's understated and rather covetable hatchback gets a soft top for the first time. More than that, it gets a record-breakingly fast one. Push the button located conveniently to the rear of the handbrake, and merely nine seconds later the canvas cover over your head will have sprinted to the back of the car and folded itself tidily against the boot. Clearly we are talking here about the Linford Christie of opening car tops, except without the somewhat distracting controversy.

Nine seconds seems to be a new world and Olympic record for this kind of thing. Indeed, it appears to have smashed the existing record for convertible top-downing into oblivion. It takes a BMW 1 Series 22 seconds to peel off its own roof - more than twice the time run by the Audi. Renault Meganes can only manage it in 22 seconds, too. A Peugeot 307 is going to need fully 25 seconds out of your day before it achieves complete toplessness. And as for a Ford Focus, you are looking at a mechanical process lasting a positively yawn-inducing, finger-drumming 35 seconds, by which time the sun will most likely have gone in again.

It takes the Audi's roof only 11 seconds to come back the other way, too, recocooning you in the car's sumptuous, faultlessly screwed-together interior. You can see the appeal of these radical roof-related time- savings, especially given the current meteorological uncertainties, as we slowly come to terms with the fact that “global warming” might not straightforwardly mean “warming” after all, but might rather mean, less enticingly, “raindrops the size of cereal boxes”.

Knowing that you and your open-top car can be out of an unforeseen, Gloucestershire-style cloudburst within the blink of an eye, brings a new confidence to al fresco motoring in the age of climate change. Eleven seconds should barely give the rain time to pool in your A3's handy coin tray. Ford Focus owners, on the other hand, in the same conditions, realise that they have a long and tiresome half-minute-plus ahead of them, at the end of which water will have flooded the interior and be slapping in waves against the CD player. And after that, they will have no choice but to retreat miserably to higher ground and damply await the cheque from the insurers.

It doesn't seem all that long ago since any act of roof-stripping from a cabriolet set one up for extended bouts of wrestling with ultimately ungovernable pieces of tarpaulin and recalcitrant poppers, endangering both one's patience and one's thumbnails. Now almost nobody gets involved personally in the unroofing of his or her car, and the manufacturers work themselves into a competitive froth over the speed of their electronic roof-opening systems. Things change so quickly.

Audi's quick-fire roof, incidentally, is powered by a “high-pressure pump and two hydraulic cylinders”, although, frankly, so rapidly does it tear back above your head that you wouldn't be entirely surprised to learn that that there was a giant Hoover in the boot, set to “suck”. Except, of course, that a Hoover would make a horrible noise, whereas, if the A3 specialises in anything, then it's in going about all of its business in an extraordinary and almost eerie silence.

This goes for the roof-opening procedure - which happens with a whisper, rather than with the exaggerated, semi-geriatric groaning that tends to accompany it in less sophisticated models - and it goes for acts of acceleration, during which the engine gives off a dimly discernible, rather expensive-sounding and altogether impossibly well-mannered, hum.

As for engine noise while idling, you probably need a stethoscope to locate it properly. At one point, I went to re-start the car, having stopped for a while after dropping someone off, and discovered that I hadn't switched it off in the first place.

Thus the chief drawback of cabriolet driving - being separated from the sound of your car by, essentially, the thickness of a tent - is somehow magically eliminated by devious German craftsmanship.

Audi's own research predicts that, for some reason, the A3 will be popular with people seeking a “second vehicle for their spouse”. They also envisage a take-up among customers with a “higher level of education and income” than their rivals. The higher level of education, we'll let pass. The higher level of income goes without saying, though. You could get two perfectly respectable cars with the money that Audi want for this one. But how quickly would their roofs open, assuming their roofs opened at all? And how swiftly would they close again in a flood? Those are the kind of considerations we find ourselves weighing up in 2008.