Currently, the method to teleport vehicles requires an absolute position. If the z-value is not correctly specified, the vehicle might end up "in" the ground. It would be useful to have a cling option to set the z-value, like the spawn method.
It is challenging to define an appropriate behavior considering that the vehicles are also rotated and the roads are not flat. In those cases, the "correct" value of z is not easily defined. Alternatively, one could specify only the 2D coordinates and orientation and let BeamNG figure out how to "rotate" the vehicle in 3D to place it on the terrain/road