There may be some confusion over the new trim level badging of these new Audis. 50 Q8 (or the other way round?) does not mean 5.0 litre, 50 is the trim level.
Doesn't the 50 relate to the KW power output of the engine? Audi dropped badging the engine litre size for the KW rating several years ago.
Read the link I posted earlier. They might say it does, but it doesn't 
This very informative link suggests that trim levels are nothing to do with engine power output, although certain engines are only available with certain models and levels of trim, varying between entry level models upto and including S and RS models.
https://www.hippoleasing.co.uk/news/different-types-of-audi-cars/And with regarding to the engne designation (bhp or kwH), this helps to explain Audis very confusing rear badging..
https://www.leasefetcher.co.uk/guides/car-technology/audi-engine-codesSo the trim levels and engine power outputs are different aspects of each model, and don't go hand in hand.
So much easier with the previous 1.2TFSI, 1.6, 2.0 TFSI, and 2.0 TDi or 3.0 TDi, 4.2 V8 etc etc
