What could be the problem if white smoke sometimes comes out the exhaust when the car is first started?
White smoke on 2001 BMW 330i
Had oil changed at a "Stealer" and then had a plume of white smoke right after start up. Looked under the hood to discover the technician (used loosely) had FAILED to reinstall the dipstick! No warning light for missing dipstick. They happened to have one lying around (yes, mine!) and replaced it "free of charge". No more white smoke and no more dealer oil changes! Good luck.
This could be an early sign of a head gasket leaking. Check you coolant level and monitor it really well, if it is dropping over the period of a week or two, have a shop check for hydrocarbons in the coolant, which would indicate a blown headgasket.