Getting all of those dead straight lines to line up perfectly and not look awful is the challenge I think. The eye is quite good at spotting straight lines, so

Getting all of those dead straight lines to line up perfectly and not look awful is the challenge I think. The eye is quite good at spotting straight lines, so a tiny difference will be obvious immediately. On a more "normally" shaped car there are curves and sweeps and things that change radius and direction as they move down the car, and other straight things like window sills etc are broken up by door pillars etc) so it is harder for the eye to ntice when things are 2mm out front-to-back.