dunno, never tried spray and I’d be a bit wary of putting it on a vehicles paintwork just in case it reacts with the lacquer.
I'm in the trade and was passed on the above by a body shop when some oik decided to "tag" my wife’s car and it worked a treat.
sounds a bit way out I know but......
Get a dry board marker and scribble over the top of the graffiti that's already their then wipe it off with a damp cloth and it brings the permanent marker off as well.....
.....just in case try the dry board marker on some paint that isn't visible...