Even when drained, most engines retain around half a litre of oil in the castings and components. You will only ever get the recommended amount in when the engine is filled for the first time (i.e. at the factory). This applies to all engines, not just Audi.
Fill according to the dipstick reading, not the manual. If it reads over maximum, the engine has too much oil in it, and constant overfilling will overstress the oil seals on the engine and cause oil leaks to spring up all over the place. The engine will also burn more oil which will eventually destroy the catalytic converter and leave you facing a serious bill.
Modern engines may be tough and need virtually no maintenance, but what maintenance there is has to be done to the letter.
1998 A6 1.8 turbo auto. Very fantastic car. I had it for 3 years, bought it at 125000 miles in 2006, now 160000 in 2009. The only problem is when the gearbox went into its backup program, selecting 4 gears only instead of all five.
I drove it like that for 2 months until I went to a gearbox specialist; to my surprise all he did was plug in a machine and reset the program, and advised me to change the multifunction switch, which I did not do up to now, and it's running smooth.
I service the car by myself, and it's easy, and also I changed the cambelt at a local Audi dealer.
This A6 is the best car I've had all my life. It runs forever, and I had no serious problems with it. I won't sell it. I am prepared to invest in it as it has done a lot of miles. The interior is still good and clean.
Thanks for reading. Ronald Madyavanhu.