One problem related to engine belts and pulleys has been reported for the 2006 Mini Cooper S. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Mini Cooper S based on all problems reported for the 2006 Cooper S.
In April 2013 I was merging onto highway i20 with my children in the back of my Mini Cooper S 2006. As I was speeding up to merge onto the highway the car completely cut off. I veered over into a median in the middle of six lanes of high-speed traffic. The car had completely shut off, even the hazard lights. I was very lucky that the median was there and that I had not yet entered the main stream of traffic. The police came, then a friend. After about a half hour it restarted without power steering and he was able to slowly drive it, and he fixed a belt that he said had looked like it had blown out. About four times in the year prior to this the car had cut off, but not while I was driving; it shut down as I was pulling out of a parking spot but then immediately restarted. No one could explain it. After the April incident I went to the Mini cooper dealer and spent close to $3000 to ensure that the car was safe for my children. However, yesterday, 11/5/13, I was backing out of a parking spot and the car completely shut down. I called the dealership for assistance and they said they had never heard of this kind of problem and couldn't help; fortunately the car restarted about ten minutes later. However, I am extremely concerned that this car is unsafe and I have heard from an acquaintance who also has a Mini Cooper S 2006 who said this has happened to her, that something random happened with her car and it completely shut down while she was driving. She told me that there was a recall, but I called Mini corporate today, and was told there was no recall and referred me to NHTSA.