Try using trisodium phosphate, or TSP. It's available in the painting aisle of most hardware stores or home center.s TSP has a paste-like consistency. Brush it onto the stain and let it sit. If anything will pull rust stains out of a driveway, TSP will. The only drawback is that the spot might end up brighter than the rest of the driveway, because TSP has a bleaching effect.