I thought about a way of detecting movement of the vehicle.
It would be something like this. You will also need another trigger or the same one constantly subtracting the death of a different unit, lets say a nuke.
QUOTE
TRIGGER
CONDITIONS:
- Computer player brings atmost 3 drone to Vulture.
- Current player suffered exactly 0 deaths of nuke.
ACTIONS:
- Create 1 Drone(burrowed) at location anywhere
- Move 1 drone for Computer Player at location Vulture
- Set deaths of Nuke to 3 for Current Player
- Preserve trigger.
QUOTE
TRIGGER
CONDITIONS:
- Computer player brings exactly 0 drone to Vulture
ACTIONS:
- Remove all Drone(burrowed) at location anywhere
- Set switch "Speed 1".
- Preserve trigger.
QUOTE
TRIGGER
CONDITIONS:
- Computer player brings exactly 1 drone to Vulture.
ACTIONS:
- Set switch "Speed 2"
- Preserve trigger.
QUOTE
TRIGGER
CONDITIONS:
- Computer player brings exactly 2 drone to Vulture.
ACTIONS:
- Set switch "Speed 3"
- Preserve trigger.
QUOTE
TRIGGER
CONDITIONS:
- Computer player brings atleast 3 drone to Vulture.
ACTIONS:
- Set switch "Speed 4"
- Preserve trigger.
I have never done anything like this, so it might not work (with these exact triggers) But it can. If you use this and it's not working, PM me the map and ill fix what's wrong with it.