Painted metallic chassis of a car is always dipped in car sized acid baths and primer baths. Dipping the whole cars held on a carriage is the only way it's done, anywhere, for any brands, using any metals, even many Ferrari, as well as with many classic car restoration projects. Your cars will be competing with brand new 1960s Fords and Mazdas if you were not doing it in terms of corrosion resistance - unless, I'm guessing, you're making DeLoreans and Cybertrucks.