The aluminum body F-150 has been out there for a while now. There are others, Acura NSX, Audi A8, Tesla, Corvette, various more exotic cars. The manufacturers of these cars recommend that any metal accessory be isolated electrically from the body. If grounding is necessary, a wire is supposed to be run to the frame rails or another designated ground point. I have an F-250 and am installing a stainless steel bracket mount that fits between the hood and the fender, under one of the fender bolts. I put some grease between the bracket and the paint. Will probably put a rivet through the side of the bracket for extra rigidity. Will probably run braid from the bracket to one of the designated ground points. Further advice welcomed. Practical experience of antenna installs on these sorts of vehicles also welcomed. I would put an NMO mount in the center of the cab except that my canoe would hit it when I have it up on the rack up there.