UV resin probably

It's a 'resin' - the technique is stereolithography (SLS) and the finished product in this case has a thin metal coating.

Just to copy

Just A 3d print enthusiast here: TL:DR, You will need to make a skeleton body, then adhere the reinforced prints onto them to have any chance of safety at 40+MPH. Every 6 or so inches will need to have reinforcement on the hood to withstand the drag forces adequately, as any sufficient flex can cause a crack and lead to cascade failure in moments at speed. Heat from the engine and other high friction area's is a serious concern as well. Do not think that just printing will be enough, this will be similar to driving with ridged paper around you at 55+ MPH, so you will need a VERY solid base structure to attach the body panels too. With the proper designs to compensate for the drag forces on connection points, it is very possible, that being said... You will want to reinforce the print with very heavy duty coating, like fiberglass and internal metal rods/structure after printing, Before attaching to the frame structure you create. If you will only need to drive the vehicle once then you can forgo fiberglass (Still coat with clear varnish for drag reduction at least), however the parts will not last long due to weak impact force from kicked up debris, salt, or even bugs. BE WARNED: The print can and WILL crack if unprotected, causing a cascade failure if driving at the time, and causing the vehicle to be inoperable.