I had the same N52 engine in my 325i and it seemed to need 500ml every 2,000 miles, but then it had done 132K when I got it.
My current 128K mile 330i seems to use a bit more, 500ml in 1,500 miles is typical.
My first E86 didn't need a top up in 8,000 miles, but it had only done 54K when I got it!
My 2nd E86 had done 76K and used a bit more, but less than either of my 3 Series. So some oil use seems normal for an N52 as mileage gets higher. A litre in 2,700 does seem a lot, but I have noticed consumption goes up when I've been heavy with my right foot.