I drive a Mini Cooper 2007. However, the way Mini BMW went about their hard to tackle electronic problems were not transparent or easy to understand.
The Mini BMW importer to Switzerland told me upon specific request that disability related car modifications were an issue that Mini resellers / garages were competent and authorized to deal with. The Mini reseller I bought the car from saw no problem with me buying it as an arm amputee.
The specialized shop providing the steering wheel knob and remote control unit, however, did not even get all functions wired up when helped by BMW specialists. The windshield wiper is not attached as there was not way to trigger that signal anywhere useful (apparently it is not present on the Mini's CAN bus).
Nevertheless, the car is fun to drive. I would recommend you to get written statements of your authorized Mini BMW dealers before buying a car for disability modification as they may not know what they are getting themselves into. Or, better probably, look at other brands.
This is the steering wheel knob / remote control. It is very functional. The windshield wiper button could not be connected but I can operate that with my arm or prosthesis without problems. Or with the left hand.