those work real well on todays bc/cc painted vehicles. on white vehicles use it at a very low speed, most of the eraser wheels are tan colored and can stain the cc on white vehicles. you'd have to sand and buff the white off......There's a "pencil eraser" attachement you can get at a body supply shop. Just throw it in the chuck of yer favorite drill and go to town. Just be careful of trim and fender edges etc., any irregularities will destroy it.
There's always better living through chemicals--- adhesive remover and elbow grease.