Manifold/header/muffler/tail Pipe problems of the 2012 BMW X6

Vehicle has been smoking, burning oil and leaving a black residue on tail pipes and on paint around tailpipes since approximately 6 months old. BMW service advised oil usage was normal for vehicle and refused to investigate further. Oil consumption has continued to increase to as much as 6 quarts in less than 5,000 miles. Having serious engine malfunctions with engine shut down, without warning and without ability to compensate for traffic conditions. Believe there is an inherent defect in the engine and that car is a danger. BMW service simply checks for visible oil leaks but refuses to investigate further.