Audi RS6

Spied here testing, the model will complete the A6 range and offer a larger alternative to the already spectacular RS4. Expected to be powered by a tuned version of the S6's V10 powerplant, the newcomer will be offered in both four-door saloon and practical Avant bodystyles.

While this prototype looks almost ready for the showroom, the new model is not expected to debut at September's Frankfurt Motor Show. Instead it will be revealed next year at the Geneva expo in March, before going on sale in the UK later in 2008.