If you look solely at its silhouette and proportion, you can trace this car’s look directly to the 'aerodynamic' Audi 80 of 1986. Such evolutionary styling, and a mechanical confection whose advances in large part lie on the option list, leave this Audi feeling slightly less novel than an all-new platform implies it might.
That said, it seems many buyers like the Audi look of one basic design in different sizes. It also has the back-handed advantage that an A4 won't date too quickly.
The A4 seems to get more attractive which each generation, as the current generation testifies. It has a shorter front overhang than before, allowing Audi to extend the wheelbase without significant impact on the overall dimensions.
The positioning of the differential and the clutch (or torque converter) has been swapped around, allowing the front axle to be moved forwards so the engine can sit further behind the front wheels.