It's not hard to guess that the latest test mule from Ingolstadt is a very thinly disguised prototype of the upcoming S8. Unlike other S6 and S7 mules that can get by with S-line garb and quad exhausts, the A8 has no S-line which makes the new treatment on the chin that much more obvious. At the rear, the usual tell-tale quad exhausts further confirm the car's S-car nature.

So what do we know about the S8? Well, for one it will make do with two less cylinders. The V10 will exit stage right and be replaced by the upcoming 4.0 TFSI that will see duty in the S8, S6, S7, RS 6, RS 7 and Bentley Continental series. Leaked Russian ETKA screen captures confirm that in S8 tune the 4.0T will be good for 518 hp. Pair that with the lighter weight of the S8 and we're guessing about 20% better fuel efficiency.



It's still not clear when the S8 will officially debut, but we expect that no later than Geneva next spring because the S8 is due even in the USA by the end of the next calendar year.

Check out the rest of our spy photos below.