Bro I am not an expert, but what I have seen is that Wd-40 eats paint. I once saw a video on youtube, a guy sprayed that on the scuff marks and boom, they were gone. I suppose such results can't be achieved without abrasion. I myself have got a lot of tar under the rocker panel area of my car + also on the mudguards. I don't think their is any cheap solution to it rather than buying a bug and tar remover. If someone has any please mention it, but it must be paint safe.