One problem related to power train has been reported for the 2006 Mini Cooper S Convertible. The most recently reported issues are listed below.
2 days after purchasing a used Mini Cooper S Convertible 2006, the car began to self shit at improper times, causing the engine to rev at high rpm's. I contacted the dealer immediately and he test drove the car trying to get the vehicle to respond the same way. After 15 minutes of driving it the problem did not occur and I was sent on my way. The problem continued to persist when I was at low speeds.