This could work very easy with the mobile part linked to the main vehicle and controlled with a move to node, unfortunately the parent-child link itself has serious problems. Nevertheless, it worth a try, it's a quick setup; also, try to avoid a simultaneous movement of the child and parent.

A

HI
Did you test with Mannequin?
I had a major problem controlling the character animation. Resolved with Mannequin.
Since you created a machine, you have to create a Mannequin.
To control the animations of the car !!
That's the only way to get it right!

Mannequin is designed to manage character animations or any entity.