Empty vehicles can change side!
If your side units jump into an empty vehicle (original class side different from yours), this vehicle stays civilian until your first man is inside. Then it becomes of one of your side (OK, it's the driver's one in fact). Make the units dismount, this vehicle returns to civilian side (normal).
Now, order the same thing to your side units, but jumping into a vehicle (supposed to be in your original side. example: Blufor Hunter or Opfor Ifrit).
First difference: the vehicle changes side (from civilian to yours) as soon as you order it. (no delay!)
vehicle will return the name of driver only when he's climbing aboard (no change).
Then, if you order all your units to dismount the vehicle, this vehicle will continue to belong to your side!!! Emptied vehicle is no more civilian!