You can use Assebly/ Align tool to align one body to another.
Anyway I suggest you first to create a plane in the middle of your car and then refer to it for next movements.
You can switch selection to only vertex mode, so you can hights three point on the middle size of your car and then you can create the plane. It will be defined in the middle of your car.
Luca
You are navigating away from the AIS Discovery experience