Unmistakably Audi. Distinctively different. The new A8 4.2 tdi carries all the design hallmarks of the Audi marque. Its restraint, purity of line and unadorned simplicity mark it out as a classic in the making. And yet there's also something about it that claims new territory; the sleek, confident sweep of its lines from bumper to bumper which belie the spaciousness of the cabin; the poise and balance of its stance. One glance, and you know. This is not another me-too executive saloon. It moves the game on. The luxury sports saloon, redefined.