Say you're using the 8-direction controls for the player and the Car movement for the vehicle:
There should be an option to disable the controls (Set Enabled), so you could do something like this:
On Player collision with vehicle (or press key etc)
-----> Set player invisible
-----> Disable 8-direction
-----> Enable Car movement
On ejected
-----> Set player position to vehicle
-----> Set player visible
-----> Disable Car movement
-----> Enable 8-Direction movement