When your window lift motor fails, it is often caused by a failure in the regulator assembly. This failure will cause premature burnout of the Window Lift Motor. Window Motor & Regulator Assembly. This part generally fits BMW vehicles and includes models such as X5 with the trims of 3.0i Sport Utility 4-Door,4.4i Formula 1 Sp ort Utility 4-Door,4.4i Lujo Sport Utility 4-Door,4.4i Sport Utility 4-Door,4.4i Top Line Sport Utility 4-Door,4.6is Sport Utility 4-Door,4.8is Sport Utility 4-Door.