It happen 4 times during normal driving on local roads on nice weather and no car infront . My car just stop violently and make a lound noise as if it hit something .It happen very quick and became normal as if nothing wrong .Reported and brought car to dealer after a week there not found any defects.The 5th times happen when car pull out from driveway with no car around. I belived this a saferty hazard because if it happen during driving on hiway i could get hit from behide for sudden stop.