Preparation :
12+ vehicle kit, maybe your hand is unlucky gacha just to be sure
A lot of medical items & bandages, this mean a lot, some turret well placed and you will hurt a lot
Stick Dynamite or Grenade, Stick dynamite has high base damage, only need 1 to destroy a turret
Bunker key from Convoy Mission reward, bring the case to trader
A sleeping bag, die and respawn near

I only know 1 locked bunker that contain mechanic tools, feels free if you know other locked bunker that contain mechanic tools

It's the bunker that near Cherny Log, near the tunnel, see the map



Find the bunker door, it's right beside the tunnel opening




Inside you need to destroy turret and beware of grenade trap, I suggest you bring 1 grenade trap and place it behind you to guard from other player you while you inside the bunker

Inside there is 3 loot room contain red welded box, you need vehicle repair kit to open it




I managed to only get 20 mechanic tools from 3 welded boxes, its the lowest yield from 4 times I went into this locked bunker, the highest yield I snatch almost 50 mechanic tools from 4 welded boxes



Congrats now you can keep your car!

It just outside army bunker