One problem related to automatic transmission has been reported for the 2003 Mini Cooper S. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Mini Cooper S based on all problems reported for the 2003 Cooper S.
My 2003 Mini Cooper S stumbles and bogs down when starting in first gear. When starting from a dead start and letting clutch out, the cars power cuts off for a moment and then cuts back in. This was not a characteristic of the car prior to my dealer upgrading the software for the engine management system. I've contacted Mini USA (aka BMW) and they acknowledge the problem, but have no fix for it. I consider it a safety issue, especially when pulling into traffic and the car hesitates badly.