If you can get a blaster it wouyld be tyhe best. But it will make a mess....

Also be careful not to use too much pressure or a non appropiate blasting media or you can risk warping the panel. Blasting straight at a 90º angle will stretch the metal and make the panel bulge and oil can. Best way is blasting at an angle lets say 30º.

If you want to try and wire wheel it also dont use too much speed as others said...too much speed and you can also heat the sheetmetal and make it warp.