The new Audi A4, codenamed AU482, will use an all-new platform which insiders vow transforms the car's dynamic abilities. The A4 family is set to grow, too, with a sleek Sportback hatch added to the staple saloon and Avant. The new A4 will debut in autumn 2007.

Underpinning the A4 is an all-new platform, undergoing hot weather tests beneath this prototype. Dubbed MLP for ‘modulare längsplattform' (modular platform for longitudinally mounted engines), this matrix is highly flexible. Modules for electronics, axles, drivetrains and suspensions are all interchangeable, allowing Audi to customise the architecture for each model. Its dimensions and content are so flexible, the MLP can support the 2007 A5 coupe and cabriolet, next A6 and new A8. And by pooling its cars, Audi will get huge economies of scale.

A4's new engines will have the latest fuel injection systems - direct injection for the petrols, common rail for the diesels. There will be three gear-boxes: a six-speed manual, the Multitronic CVT, and the twin-clutch DSG gearbox (or S-tronic in Audi parlance). This gets an additional, seventh gear and can now handle 368lb ft of torque.

Audi plans to apply the A3 Sportback formula to the A4 platform. Untill autumn 2009, the A4 Sportback will be a sleek, five-door hatch, with heaps of interior flexibility to offer a good balance of people- and/or cargo-carrying. The Sportback will be a little shorter and less capacious than the Avant, and it gets a bespoke rear end. Another possible bodystyle would be the Roadjet, Audi's concept at the 2006 Detroit Auto Show.