The wheel arch extensions seen on this car look as though they might do service on the upcoming A4 Allroad, but this prototype's S4 base, fat rear wheels and low profile tyres hint at something altogether more sporting.
If parts from the next-gen RS4 are indeed lurking beneath the surface, we can once again expect a widened stance at both ends and subtly flared fenders. The small disc brakes indicate that the new RS4 Avant is still a while away from being production ready, though.
Our photographers weren't able to give us any indication about the drivetrain lurking beneath the mule's bonnet. The outgoing RS4 Avant featured a 4.2-litre V8 with 331kW of power and 430Nm of torque.
Allied to a standard all-wheel drive system and a seven-speed dual-clutch transmission, that drivetrain was good enough to move the hot wagon from 0-100km/h in 4.7 seconds.
Given the industry wide trend towards smaller turbocharged engines with fewer cylinders, the naturally aspirated V8 may give way to a more powerful version of the direct-injection turbocharged 3.0-litre V6 used in the new S4.
With 260kW and 500Nm at its disposal, the all-wheel drive, eight-speed automatic S4 sedan is also capable of a 0-100km/h time of 4.7 seconds.