Oil consumption

[bmw5]

My car (X3 2,5 si) since the very beginning has been emitting white smoke from the exhaust.At the workshop i was told that this is normal,it is vapor which sits on the exhausts and when firing up it becomes smoke.This doesnt happen en route but after starting the engine.A week ago the yellow oil symbol along with an accoustic signal and the warning on the screen "add oil 1 littre" came on.I have only covered 1600 kms and i believe is very soon for the engine to complete 1 littre of oil.My quess is that the engine consumes too much oil hence the white smoke.The oil warning stayed on for a couple of kilometres and erased on its own.At the workshop they added some oil and neither were they alarmed for the oil consumption nor for the white smoke.In fact i was told that it is normal to consume 0,750 litres of oil at first 2000 kms as the BMW factory instructs but i have only covered 1600 kms.Any ideas for the white smoke and if is it normal to add oil at 1600 kms?Do you have the same oil consumption?