This is our first look at Audi's new A3 Cabriolet, which will go head to head with BMW's recently announced 1-series Convertible when the two cars are launched next year.Like the BMW, the new A3's most obvious rival, the Audi uses a fabric roof instead of the folding hard-top more commonly found in cars of this class.Audi has always said it won't use folding hardtops on any of its models, because it doesn't want to add the weight and complexity of the extra metal and the folding mechanism.This philosophy benefits smaller cars, like the A3, the most. The rear seats stay useable, instead of being shrunk to 2+2 proportions, and the boot doesn't get smaller when the hood is folded. The weight, always an issue in a cabrio because of the strengthening needed to compensate for the loss of the roof, is kept down and that means better performance and better emissions.The roof will be available in two specifications: semi-automatic and fully automatic, which is better insulated for sound reduction and warmth.The boot has 260-litres of space, unchanged whether the hood is up or down, extending to 674-litres with the rear seats folded. The hood itself comes in three colours: blue, red or black.Engine choices will be limited to four four-cylinder units, two petrol and two diesel. The petrol units are both direct injection TFSI engines; a 160bhp 1.8- and a 200bhp 2.0-litre. The TDI diesels, a 1.9- and a 2.0-litre, have 105bhp and 140bhp.The quickest A3 cabrio will be the 2.0-litre petrol, available with a dual clutch box as well as a six-speed manual, which reaches 62mph in 7.3sec. The 1.9-litre diesel A3 won't be challenging even the 118i Convertible though - it takes 12.3 seconds to get to 62mph.The A3 Cabriolet will go on sale in Spring 2008. Prices haven't been announced, but expect to pay around £20,000.