Platform/Model management - minor visual changes for models?

Hi. I've searched for this so sorry if this is a repeat, but the main thing that I think could be improved/streamlined a bit is the way that "platforms" and "models" vary.
Currently, you can't change much about the way a given "model" looks - that has all to be done in the "platform" builder. this makes sense to a degree but makes the process of, say, having a range cars from basic to sporty on the same shell difficult. so what I'd propose is the following.
The model builder should let you add/delete/move the following visual items:
Wings
Lips
Vents
Exhausts.
Bonnet bulges
And should let you alter (but not Add, Delete, or Move) the following where there are subtypes (example, when you select a tail light shape and then there are "normal" and "altezza" variants).
Grills
Headlights/Tail lights/indicators
Handles.
So you can then tweak the visual trim level, wings and so on of the parts that are "bolt on" and then have a single platform that can range from a basic car, to a blinged-up chrome-laden luxury model, and a bewinged hot version off the same "Platform."
Currently, you can't change much about the way a given "model" looks - that has all to be done in the "platform" builder. this makes sense to a degree but makes the process of, say, having a range cars from basic to sporty on the same shell difficult. so what I'd propose is the following.
The model builder should let you add/delete/move the following visual items:
Wings
Lips
Vents
Exhausts.
Bonnet bulges
And should let you alter (but not Add, Delete, or Move) the following where there are subtypes (example, when you select a tail light shape and then there are "normal" and "altezza" variants).
Grills
Headlights/Tail lights/indicators
Handles.
So you can then tweak the visual trim level, wings and so on of the parts that are "bolt on" and then have a single platform that can range from a basic car, to a blinged-up chrome-laden luxury model, and a bewinged hot version off the same "Platform."