Audi is currently developing the next generation Audi A6, which is expected to be the German brand's last model powered by a combustion engine. Most of the camouflaged Audi A6s we've seen so far have been the long-wheelbase Chinese-market version and are unrelated to models the rest of the world will see, but these new prototypes and mules caught in the wild by our spy photographers are the first in the series of the next-generation Audi A6 for the rest of the world. They include the S6, replete with voltage warning stickers and a charging port on the left rear fender, signifying it's a plug-in hybrid.

The models our intrepid photographers spotted feature several different drivetrains and body types. Engines are hard to discern, but it's easy to spot sedans, wagons, and the high-performance S6 model. Unfortunately, the bodywork from existing models suggests an evolution rather than a revolution for the A6. The interiors of the cars are a combination of parts that tell us the prototypes are still doing their job and working to finalize the design.

It's likely the engine choices will mostly carry over to A6 models and include the current 2.0- and 3.0-liter turbocharged engines.

Whether the cars will reach the market as the A6 and S6 are in question, as Audi's CEO, Markus Duesmann, has put out there that Audi may change its naming convention to take into account electrified vehicles. The idea floated by Audi is that all-electric vehicles would have even numbers, and combustion vehicles would use odd numbers. If that's the case, then the A6 we see here could hit the market as the A7 and the S6 as the S7.

While the A6 (or A7) is being developed, the A6 e-tron seems to be closer to completion, and it runs on the same platform as the Q6 e-tron. Overall, this isn't going to be an easy year for journalists trying to keep track of Audi's lineup and keep track of the Audi naming conventions.