I would like to see some maintenance feature in the game, where you need to turn off on a scheduled maintenance plan.
You can choose maintenance on a regular basis, but the machines will be down more and you will make/sell less cars. Or you can choose to do maintenance far in between but then the chance for malfunctions will get higher the longer the time passes after last maintenance.
When a machine malfunctions, anything that machine was working on will be scrapped and repair will take longer than regular maintenance will.
QA doesn’t seem to do much right now either and would be nice to have 2 output conveyors, one of approved cars and one with rejected cars.
The rejected cars can be led into a new station that will be able to restore the flaws in the car and then send it back through QA station again.