Congratulations! Is the noise you are referring to inside the cabin or outside? At idling or under driving conditions? Also, the noise levels you are comparing are of the same car, right? Since yours is a new car the engine noise might need some getting used to. Anyway, if you have the time, do get it checked at the FASS for your peace of mind. Better safe than sorry! As you might be aware, in many countries, as a rule, children have to be seated in the backseat. Therefore the power windows of only the rear can be disabled. Once you engage the lock, the back-light of the window control switches at the rear, as well as their operation, is killed.