Thank you for your response.
We did the evaluation on the zinc coated option, from pure technical point of view. Also I used a lot of zinc coated sheet metals in my previous business. I was the founder and CEO of USSV, and we built Rhino GX and Rhino XT vehicles in small volume production. All our vehicle bodies were hand welded from zinc coated sheet metal. Using zinc coated sheet metals was not because we wanted , but because we had no choice. No matter how much protection the panel is, the rusty area is always at the welding zone. The welding process will damage any rust protection and produce smelly smoke. Most of the time in order to avoid the smelly smoke from the welding, operators always ground off the surface coating. After welding, we applied primer to cover it, but it will rust anyway after a certain period of time.
Actually in China, the zinc coated sheet metal is cheaper than the steel we are using. Using zinc coated metal will produce a lot of smoke during laser cutting and welding, and the cutting edge is not as clean. Another reason is that, even if we are using zinc coated sheet metal, we will still need to weld them together and still need to put in e-coating to protect the welding area from getting rust.
All I say here is just an explanation from pure technical point of view to put my two cents in. Nothing offensive.