In the prices menu, clicking on an item gives you a pop-out breakdown of what is needed to produce that item, or if it’s outside purchase only.
For example, Powertrain takes some items to assemble. A Super-fast Powertrain uses additional items. I would like to find out what additional items would be necessary to add that feature to a vehicle, before I commit to offering it.
If the necessary items can be manufactured, I can get the manufacturing in place before the workstation upgrade is applied, since stock is now available. (Or decide to not offer the upgrade due to current resource constraints.)