I fail to see how adding upgraded sound system to the upgrade package makes things simpler. If you are running multiple kinds of cars on the same production line (and they have to be), each station needs to assess whether to add a bit, looking to see if some other bit was also added is a terrible way to do that. Each car needs to be spelled out whether that part goes on the car, either to the human or the robot adding the part. If we just start with the things we know will be options we get 9 colors, AWD/RWD, 2 battery sizes, ludicrous, tow, 3 roof options, wheels, we get 50,000 different kinds of cars. Tesla has figured out how to option a car, now they will add how to make them fast when they are designed to be easy to make.
Thank you kindly.