We knew already that Audi is preparing a facelift version for the A6. It was caught testing many times before, including back in February 2022, when two prototypes were spotted standing together in the parking lot.

But, this recently spotted Audi S6 is really raising a lot of questions. First of all, it is a U.S.-spec S6 testing in Northern Europe, but most importantly, according to our spy photographers, it was making a very intriguing sound.

Apparently, the car was very loud, and only when looking from the back you can understand why. Usually, the S6 is offered with quad exhausts placed on both sides of the rear bumper. This prototype, however, has two more central-mounted exhaust pipes that make the engine very loud.

Of course, these pipes look very provisional, but there is also a strange box under the car on the left side next to the exhaust. It is of course missing on the opposite side, so it really raises more questions.

Also, you can easily see that the car is sitting very low - lower than any S6 we've seen before. So, the question is: what is Audi testing here? Could it prepare a more serious competitor for the next BMW M5?

Your guess is just as good as ours, but, if we'll let you know when we get more details on it.