triggerName triggerAttachVehicle  or [vehicleName]
: Object or [vehicleName]
Type of returned value
If  is given, the trigger is detached from the assigned vehicle.
If the activation source is one of:
The activation source is changed to "NONE".
If [vehicle] is given, the trigger is attached to the vehicle or its group.
When the source is:
It's attached to the group, otherwise it's attached to the vehicle and the source is changed to "VEHICLE".
trigger triggerAttachVehicle [player]