Facelifted performance wagon snapped on Europe's snowy roads, with mild design revisions the most obvious changes.

The upcoming refresh for the Audi RS4 has been spotted during cold-weather testing, giving us an early look at the design changes in store for the flagship A4 Avant derivative.

aGiven the swirly black-and-white camouflage is concentrated around the front and rear ends, that's likely where the majority of the (subtle) changes will be made to the design.

Up front there's revised headlights, and a more three-dimensional grille design that should echo the look already seen on the likes of the Q3 and Q8 crossovers.

Meanwhile, the LED tail-lights have been given a more 3D signature as well, in keeping with Audi's latest models.

It's likely the bumpers will receive minor redesigns, while new alloy wheel designs should be offered as well.

Under the skin, it's unclear whether the current 331kW/600Nm 2.9-litre twin-turbo V6 will get any significant upgrades, though as more stringent emissions regulations come into force in Europe, there may be some changes to reduce CO2 output.

No clear images of the interior have been provided with this set, though it's possible the RS4 could get an updated infotainment setup incorporating a larger screen and Audi's latest infotainment software.

Stay tuned to CarAdvice for all the latest over the coming months, and click on the images for the full gallery.