I have had my 1M just over a month and have driven just over 2k miles. My kids who are 6'1" and 6' have not complained about sitting in the rear seats, they are however comparing the rear seats to our old e46 and our current second car which is a mini.
I have also spent a little time in the back seats and for the hours drive i was there it was ok for me and i am a 5' 11" 200lbs male.
I would suggest that you get yourself down to your local BMW dealer and check out a 1 series coupe for yourself
