Since the doors and bodies come from separate production lines, you could use computer vision to very accurately measure them and then match up those with the b

Since the doors and bodies come from separate production lines, you could use computer vision to very accurately measure them and then match up those with the best fit so you need to do the least adjustment. Alternatively you could pre-bend the doors in a machine for each body, after welding. But probably cheapest indeed to have a station late in the assembly line with people manually twisting the doors to fit, as is the standard practice.