This is not a disagreement to anyones comments, but I would hesitate to use the angle grinder and wire brush inside the car unless the interior is completely stripped. Its going to wrok really well, but its going to make a pretty impressive mess.
The inisde is easy. Just keep telling yorself how much worse it would be to be laying on your back with an angle grinder for 8hrs removing the undercoating from the other side of the floorpans and you will be done in no time
