I thought the Chinese factories liked to keep tooling for one project together. i.e. a new underframe tool will be made for the car-flat (as a copy and paste) that can then be kept with (or is part of) the rest of the tooling for the car-flat specific parts. That way the tooling required for a model isn't stored in another factory across town. For the car flat it would also mean that parts that aren't needed like battery boxes and dynamos don't have to be produced.
Edited by Steven B, 30 November 2016 - 13:17 .