NHTSA complaint #11394561

Owner complaint summary

THE VEHICLE HAS E-ACTIVE BODY CONTROL (E-ABC), WHICH HAS DIFFERENT DRIVE MODES THAT AFFECT TRANSMISSION SHIFT POINTS, STEERING INPUT AND SUSPENSION. THE VEHICLE HAS THE OE WHEELS AND TIRES (COOPER ALL-SEASON TIRES). ONE DRIVE MODE IS DESIGNATED 'CURVE,' WHICH CONTROLS BODY LEAN IN CURVES. DEPENDING ON THE SETTING, CURVE HOLDS THE BODY UPRIGHT OR SLIGHTLY LEANS IT INTO CURVES, LIKE A MOTORCYCLE LEANING INTO A CURVE. WHEN IN CURVE MODE AND DRIVING IN A CURVE, THE VEHICLE'S SAFETY OR ACCIDENT AVOIDANCE MECHANISMS MAY UNEXPECTEDLY INTERVENE FOR NO APPARENT REASON, CAUSING VEHICLE INSTABILITY AND AN UNEXPECTED CHANGE IN THE DIRECTION OF TRAVEL. THE VEHICLE BEGINS TO YAW IN ONE DIRECTION, GIVING THE SENSATION OF SLIDING ON WET OR ICY PAVEMENT, AND THEN THE VEHICLE 'BRAKES' ON ONE SIDE, 'PULLING' THE VEHICLE TO THAT SIDE. SOMETIMES THE DRIVER'S SEATBELT WILL TIGHTEN AND OCCASIONALLY, THE 'TRACTION' LAMP ILLUMINATES IN THE DASH. THE ROAD SURFACE IS CLEAN, DRY AND FLAT AND NO LOSS OF TRACTION OR POTENTIAL LOSS OF TRACTION OCCURRED. THIS HAPPENS MORE DURING CASUAL DRIVING THROUGH CURVES THAN WHEN AGGRESSIVELY DRIVING THROUGH CURVES. THIS FIRST TIME IT HAPPENED, THE VEHICLE WAS EXITING A CURVE TO THE RIGHT AND THEN ABRUPTLY YAWED TO ONE SIDE AND THE VEHICLE CROSSED THE CENTER LINE, BEFORE STRAIGHTENING AND RECOVERY. ON ANOTHER OCCASION, THE VEHICLE WAS ENTERING A CURVE TO THE LEFT AND IT ABRUPTLY YAWED AND WAS PULLED TOWARD THE SHOULDER OF THE ROAD BEFORE STRAIGHTENING AND RECOVERY. THERE HAVE BEEN MORE THAN A DOZEN OTHER INSTANCES. THE ROAD SURFACES HAVE ALWAYS BEEN CLEAN, DRY AND FLAT ASPHALT PAVEMENT. ON ONE OCCASION A MERCEDES SHOP FOREMAN WAS IN THE VEHICLE TO WITNESS THE EVENT, WHICH HE DESCRIBED AS AN 'INTERVENTION.' THE MERCEDES BENZ DEALER HAS NOT BEEN ABLE TO DETERMINE THE CAUSE OF THESE OCCURRENCES OR TO FIX THE PROBLEM.