If its just a surface mark, then something like Autoglym Super Resin Polish applied with some pressure over a few passes should take it off. But if you rub your finger nail over it and it catches (goes in the groove) then it will more than likely require wet n dry and a few passes with a machine. But definatly give the super resin a go, its pretty cheap and used correctly can give really good results.
Basically my dad has a V reg ka which on the last mot had an advisory for rear suspension struts need attention. Mot time is now due and there is a large gap (about half an inch or so) between the rubber and the top of the strut in the car. Does anyone have any idea what we will need to replace? We did think it might just require a spring, but not too sure, so thought I'd ask the experts lol. Any advice much appreciated. Thanks.