I need 2 new fenders, I want to replace them with fiberglass ones to save weight, but the car will be used on the street. Is there any bad things about using them on the street.

 

Not really.

#1 the weight saving won't be very much. Fiberglass is actually heavy and the weight of the fenders isn't very much to begine with.

#2 Fiberglass parts are not direct bolt on and paint items. They're never 100% after coming out of the mold so they need to be prepped and smoothed before painting.

 

Third gen fenders are fairly light as they are due to the full unibody, now pick up a second gen fender and you'll feel some weight.

 

the only reason why i was going to do it was to save weight, but since there isn't much difference, i'll stick with the steel ones and save my self some time, thanks !!