Sarge is right on this one. Years ago, in a different life, I managed an automobile cleanup shop for used car dealers. Clean glass was critical - even to the point of cleaning the side windows down an inch to make sure there was no "line" 1/4" at the top where it rests in the door frame. We used vinegar, water and crumpled newspaper; the only caveat is that you've got to not over do the vinegar or your MM will have a non-factory authorized odor <g> and the newsprint will come off of the paper onto your hands or upholstery, so don't leave the old paper in the car as you crumple up a new sheet.
Some commercial products work well too, but I've never had a problem using vinegar/water (assuming the temperature is above 32 degrees f.!)
Your mileage may vary <g>.
Jim