Audi's next A6 will debut by the end of the year.

Audi's next-generation A6 sedan has finally broken cover while undergoing cold weather testing. The A6 seen here will go from prototype to production model in less than a year's time.Caught testing alongside the current version of the sedan (albeit in S-guise), it's clear that the fifth-generation A6 will adopt styling language from the new A4 and the upcoming A8 flagship. Up front we see a new grille design and thinner headlights with a more distinctive surround. Despite the changes, the A6 is still easily identifiable as an Audi.

In profile the new A6 appears to have a large greenhouse, which should translate to a roomy cabin. The rear of the car remains heavily camouflaged with prototype-spec taillights.

According to our spy on the ground, this particular A6 model is either a hybrid or an Ultra model with improved aerodynamics. However, the entire A6 range should feature a slipperier shape for improved efficiency.

The 2019 A6 will be available almost exclusively with four- and six-cylinder engines. The lone exception will be the RS6, which is expected to use a 4.0L twin-turbocharged V8 borrowed from the Porsche Panamera Turbo.

Inside expect a high-quality cabin with advanced technologies like the next-generation of Audi's Virtual Cockpit. A full suite of semi-autonomous tech is also expected.

Audi is expected to unveil its 2019 A6 at this fall's Frankfurt Motor Show. Sales will commence sometime in 2018.