Dealer maintenance extremely expensive. Various convenience features, activated by pressing buttons on the key, may turn on unintentionally, so some dealers were instructed to deactivate them or change the system of pressing buttons. Dealers were also instructed to replace a faulty clamp on the exhaust hanger. In early models, rattling noises are caused by loose nuts on the stabilizer-bar links. An unknown percentage of M96 engines suffer from intermediate shaft failure, a design flaw that destroys the engine with little warning. Another possible problem is the rear main seal leak that can cause oil loss and damage the engine, requiring pricey replacement.