One problem related to engine overheat has been reported for the 2007 Mini Cooper S. The most recently reported issues are listed below.
My 2007 Mini Cooper S thermostat housing has started leaking to the point that it would cause the engine to overheat at prolonged stops in traffic if fluid is not put in the overflow tank. I have been reading various threads regarding this issue and see that there are several reports of this failure, however Mini does not seem too worried about this part.