A bit late but I agree with lordrobs, the doors are probably the original direct gloss (ie not clearcoated) finish, hence why they have faded like that.
Even from those pictures I can clearly see that the front end had been painted, almost certainly in a base & clear finish (extra film build at the panel edges). Rear quarter and sill looks a different colour in the last shot too. That could point towards a rear arch/sill repair in the past since the MX5 are so prone to rusting in those areas
Even from those pictures I can clearly see that the front end had been painted, almost certainly in a base & clear finish (extra film build at the panel edges). Rear quarter and sill looks a different colour in the last shot too. That could point towards a rear arch/sill repair in the past since the MX5 are so prone to rusting in those areas