 After software updates failed, replaced entire radio/bluetooth/nav system (covered under warranty, but multiple dealer visits).  Replaced rear differential (covered under warranty - no loaner car, multiple day repair).  Now at 18 months and 24k miles, not only are the rear brake pads gone, but the rotors gone as well.  Car is driven under normal conditions and front brakes are fine (at least at this point).  Mazda agrees that they wore quickly, but will not cover or partially pay for repair.  My first Mazda purchase and possibly my last.