I understand that the game is a simulator but I have an idea where you can collect power-ups that repair the vehicle, replenish ammo and refuel.
Can be spawned randomly on map or spawn from every destroyed vehicle
To collect them you have to fly/move/swim on them or shoot them down

-Flying vehicles these would look like balloons

The green balloon repairs aircraft
the red balloon replenishes ammunition
the blue balloon reuel

Land vehicles instead balloons have wooden crates with symbols
Wrench repairs vehicle
Bullet replenishes ammunition
Red Jerry Can refuel

Water vehicles uses buoys with blinking light on top in same colors just like balloons