I check my oil level every few days
AFAIK dealers have told me that the guage reports OK most of the time. It will only ever tell you fill up 1ltr at the most.
Most new cars will burn some oil regardless if they are thrashed or driven lightly. Some manufacturers have very loose expectations on what is acceptable usage. My lease company quoted me 1ltr per 1000 miles!!
The engine should stop drinking oil after sometime. My 320si has done nearly 20k and consumed one litre of oil so far. The current guage reading is nearly at low level. I won't be topping up as it goes in for its first service next week.
Its already showing 800 miles over the service indicator. The wondered how CBS affects warranty, apparently BMW don't mind the service indicator being 1000 over.