Audi A4 convertible: Roofless efficiency

Richard Dredge finds getting to grips with Audi's new fast and easy topless models a real turn-on

There's something in the British psyche that says a convertible car is a covetous thing - despite a climate that hardly lends itself to wind-in-the-hair motoring for much of the year. We also like our premium badges, so put one on a drop-top and you're onto a winner.

That's why companies like Audi, BMW, Mercedes and Saab do so well with their convertibles over here. But now there's a third element - the diesel engine. We're buying ever more oil burners in the UK, so stick a DERV powerplant into a premium convertible and the chances are you'll be fending off customers at the showroom door. Well, that's what Audi is hoping.

Six engines are available in the new drop-top A4, and it's significant that the most popular is expected to be one of the two diesels on offer. If the idea of an oil-burning convertible is anathema to you, try Audi's new 3.0TDi version and you'll soon be converted.

It's so good that, having started off my introduction to the new range by driving this version, the rest of the offerings paled into insignificance.

Well, aside from the range-topping 344bhp V8-engined S4, which will account for just 4 per cent of Cabriolet sales thanks to its price and thirst.

The revised Cabriolet brings with it the Audi family face and a better roof mechanism, which opens and closes faster (just 21 seconds either way) and can be operated on the move up to 20mph. For £200 more you can also have an acoustic roof, which cuts noise (when raised) to saloon-like levels - and it's well worth it.

However, the big news is the introduction of the two diesel engines, including the fabulous 3.0 V6 TDi unit and the 2.0 TDi four-cylinder powerplant much vaunted elsewhere within the VW/Audi group.

There are also four petrol engines; the 1.8T is carried over from the old range, and this is joined by the turbocharged 2.0-litre powerplant seen in the much-acclaimed Golf GTi.

If you're a press-on driver addicted to petrol power, you'll want the 3.2-litre V6 or the 4.2-litre V8-engined S4, the latter also being carried over. Which model you go for depends on your budget, choice of soundtrack, and how quickly you want to go.

Being the cheapest derivative, Audi reckons the 1.8T will account for nearly a third of Cabriolet sales. While this and the 2.0T (£27,385) are inoffensive enough, they're a bit breathless and expected to be outsold by the 2.0TDi, which is much more parsimonious and costs just £26,575.

There were no 2.0TDi models to try, but it's almost certainly going to be better to drive than the smaller petrol engines as well as making more sense financially; the only potential stumbling block is how much clattering there is from the engine room.

Discounting the S4, the priciest Cabriolet is the 3.0TDi; at £32,735 it costs £200 more than its 3.2 V6 petrol sibling. Frankly, anyone who opts for petrol power from these two is daft, with the diesel offering similar performance but far better fuel economy.

It's not as though the oil-burner is rattly either; as soon as you fire up the 3.0TDi it's smooth and refined, if not altogether silent with the roof down at low speeds.

Explore the rev range a little and there's a noise like a raspy four-cylinder petrol unit; it doesn't really ever sound like a diesel. Tapping into the huge wave of torque that's available is simplicity itself, with phenomenal performance on offer at any speed. It's best to have 2000 revs on the clock to accelerate with any real alacrity, but the car will easily pull from barely half that.

Having sampled manual and Tiptronic gearboxes, both equipped with six ratios, it's the self-shifter that stands out. There's a 3mpg and £1400 penalty to pay while it takes half a second more to get to 60mph, but both cars can manage a purely academic 150mph.

What's impressive is the way the power can be exploited so easily, with Quattro four-wheel drive as standard on all but the four-cylinder cars; these get front-wheel drive instead.

The ride/handling balance was one of the few criticisms of the old Cabriolet, so Audi has now fitted front suspension based on the A6's and rear suspension on the high-performance S4's.

The result is a car that rides well even on broken surfaces and handles predictably, if a bit anodyne. That's despite a new speed-sensitive power steering system being fitted, in a bid to improve steering feel - it still feels typical Audi.

Ultimately, it doesn't matter which version of the Cabriolet you go for, as it's a superb all-round package. Well screwed together with plenty of equipment, the driving experience is good, if not especially tactile.

Space is adequate for four and the roof mechanism works beautifully. The question is: just how will they improve on this one, unless they break all the Audi rules and offer a real driver's car?