oil consumption

[Roadster]

I got the low engine oil warning yesterday
my 3.0d has a bit under 9.000miles
when checking both the iDrive menu and the dipstick (yes, I've got one), the oil level was indeed at the minimum mark, so I added 1l of oil
I'm amazed that the engine oil level gets to minimum after only 14.000kms... Breaking in was done as it should and I allow for the engine to warm up gently before putting my foot down.
Anyone else encountered the same issue?
I did have a 300mile trip last week where I was in a bit of a hurry and hardly ever got under 90-95mph... maybe this burnt some of the engine oil, but at that speed the engine makes about 2900revs, not even close to redlining...