A car kit is a whole car, or a part of it (nose cut / body kit).
If you work with machine kits, it would be convenient for you to know how much you have earned on a particular machine kit, to find out its payback. To do this, before adding spare parts to a car, create a car kit in the "Machine kits" section. In the future, when adding spare parts, you will not need to specify the parameters of the car each time, such as the make, model of the car, since they will be duplicated from the parameters of the car kit.