You can write your topic however you want, but you need to answer these questions:
I am currently trying to build a vehicle chassis to use. I have been able to implement an automatic gearbox in the forwards direction only, but…
I need to find a way to check if the occupant of the vehicle is pressing a given key, like “F” “R”, so I can implement a way to allow the vehicle to reverse.
I looked at UserInputService but that requires a LocalScript that can’t be on the vehicle itself - and the chassis needs to be self-contained so it can be easily inserted into a game without any extra steps.
The only way to detect key presses is in a local script. You can detect for input in the LocalScript, then use a RemoteEvent to tell the server script to move the car. It wouldn’t exactly be self contained like you said, but it’s just 1 local script to move into StarterPlayerScripts.
Dissecting the AC6.81 chassis appears to show that the physical parts of the vehicle must be set up with a normal Script, but the driving script can be run using a LocalScript whose parent is a PlayerGUI (which I was planning to implement at some point). Inside that LocalScript, I can use the UIS, thus solving this problem.
This brings up a different problem; should I take this to another post?