A long long time ago there was a bug that existed that allowed you to have "floating parts". That screenshot is from the current version, but it illustrates my point. You could hover your cursor over a part, have it highlighted like above, and exit the menu and the part would stay highlighted and isolated from the rest of the car. I loved it and was devastated when it went away. It would be a great idea to introduce it back to the game as a feature, as it went very well with the game. That bug allowed us to see how parts worked towards the whole of the car. You could isolate just the springs and see how they worked, or see entire axle work together in unison. I'd love to be able to just drive around with the drivetrain and see how it works under the rest of the car. It was a beautiful bug and it should be brought back.
I think this would be a helpful and educational feature and agree with the suggestion enough to show my support for it. Perhaps limited to within free roam mode and for sections of the running gear (ex: front/rear suspension assembly as independent options to view).
I wonder, can you do the same but have just the body and chassis disappear? Have the suspension, engine, and drivetrain visible but the body and frame invisible.