Do you know that the vehicle wrapper is not the script?
The vehiclewrapper script just mounts together the parts of the vehicle. If that is done the script is not needed anymore.
If you think about the powertrain script, that just applies some input to the (still mounted) vehicle wrapper. If you do not run that script, the vehicle objects still work. But does not receive any input (steering, power etc.) and therefore just staying around (maybe rolling down a hill).
-> conclusion not running the scripts do not remove the vehicle. You just do not use it.
An alternative way would be:
Remove all objects of the vehicle (body + wheels). Replace them with the same objects, but not mounted.
Unfortunalty if you run 2.49b and you remove the wheels, the BGE will crash :(.
That means you can’t remove a vehicle without switching the scene (this is possible).
I haven’t checked if the BGE crashes if you disable physics before removing the wheels.
Sorry I can’t help you with that.