Hello folks! Today I will be showing you how to set up A-Chassis mobile support by @ChadErgus1, so let’s start.
1st part
Get the model: A-Chassis mobile support - Roblox
In studio, open the toolbox and go to inventory and insert it to the game.
When you insert it you will see the model apear in Workspace.
Click on the “>” to open up the model’s children.
Inside you should see 2 local scripts. One named Mobile Support and the other named ReadMe.
If you click on the “>” on the Mobile support script, you should see a frame called buttons. Open up buttons and you will see all the buttons to drive the car with. Without further ado let’s move on.
Open up the car model’s children and open up the Module script that’s called A-chassis tune, and inside you should see a folder called plugins.
Move the A-chassis mobile support script to plugins.
2nd part
Open up the A-chassis mobile support model and open the ReadMe script.
Select the whole script and copy it (ctrl+c).
Open the car model and go into A-Chassis tune then go into A-chassis interface and open up the Local script called Drive.
Scroll down until you get to a line that says: --Drivetrain initialize and paste the copied script on top of --Drivetrain initialize.
End
Now your mobile supported car is done. 
Credits
@ChadErgus1 - GUI design
@EOASTUDIO - Scripting
Feel free to give feedback