The galvanising should be obvious, the zinc should show as a grey metal on the chassis as you often see on industrial fencing.
It should be an M16 car.
The body might be mild steel or ali. Take a small magnet to check. The bulkhead / firewall is mild steel and as said can rust. If it has a tool box on the bulkhead check for rust under the mat the tools sit on. That is the part of the car supporting the steering wheel shaft so rust isn't good.but it can be fixed.
Check it steers straight with no Malvern dance at c 60 mph. Does it brake in a straight line?
