If the scratches or dull spots on the fender are not to deep in to the paint , or just the clear coat is scratched or dull areas, they can be buffed out , if there is many scratches start with a heavy rubbing compound like No7 rub steady but take it easy dont use to much pressure untill you get the feel . When you wipe it off you will want to see a uniform look in the area rubbed if it is not even do again till you get this uniform look in the area, after you have that ,move on to a fine compound (polishing compound) apply the same as above, then I use mothers mag & alumimun polish and apply the same as above, I dont like mothers as a metal polish but it does make a exceptional very fine rubbing compund for clear coat paint. then I would use 3m filling glaze (swirl mark remover) then give a final wax. if the scratches or dull spots are lite and only in the clear coat skip the heavy rubbing compound and start the fine compound then the Mothers alum polish and so on, take your time use good clean rags and you will have good results.and repeat steps if ness.
