White smoke coming from rear on 2003 745i - 2010 BMW 7 Series

the main problem caused by white smoke is either steam which is head gasket leaking water into cylinders /and will also have condensation or water out of the rear end exhaust ,or if running ok and no loss of water in radiator and starts ok then could be a mix of fuel .but if you are loosing water then its the first problem.
As if it was oil burning then its black smoke you should have not white.

http://www.carsdirect.com/car-repair/causes-of-white-exhaust-smoke


Causes of White Exhaust Smoke

is this well vehicle is running and coming out of exhaust pipe. If so keep and close eye on engine coolant. white smoke usually from water or mosture be burnt in engine

THE E BRAKE SHOULD HAVE CAUSED SMOKING AT REAR WHEELS IF LOCKED ON....ENGINE SMOKE SOUNDS UNRELATED.
*** DID IT STILL SMOKE AFTER RELEASING E BRAKE?

WHAT COLOR IS SMOKE IF ITS WHITE YOU HAVE BLOWN HEAD GASKET IF YOU SEE WHITE STEAM SMOKE UNDER HOOD OR WHITE SMOKE COMING OUT THE EXHAUST PIPE.

Yes the white smoke from the rear at the wheel means that the breaks need to be changed/replaced.

White smoke is usually the sign of a blown headgasket.. I would have the coolant system pressure tested before any serious damage is done.

White smoke + engine not fully working = head gasket failure. Replace it.

White smoke is not good. But it may not be what white smoke typically is, which is coolant leaking into combustion chamber... but rather a backfire dislodging exhaust particles.

Get the error codes read and you will be able to know where to go next.

u have oil leaking on the exhaust system, have the car put on a rack and check for the source of leak.