I think I have suggested something similar before, but I can't remember
It would be cool if we could tie units together sort of like how boats and trailer vehicles work so that they always respond with the other if either is selected. Having a "2nd piece" that goes with a specific vehicle.
This sort of ties into my previous post about hazmat and expanding the SOC side of the game but heres the units that would tie together and with what
Engine + Decon/hazmat unit (think FDNY HMTUs that follow the engine for calls, would have min of 1 and max of 4 and require hazmat training)[Blocked Image: https://i.ytimg.com/vi/CaCqB-OmuGY/maxresdefault.jpg]
Ladder(platform truck) + chemical decon unit (think FDNY CPC truck that follows the ladder to decon calls, min 1 max 2 requires hazmat training, i would say have a new training class for decon but I think that would make it too in depth and not really needed for a game)
Rescue engine + squad unit (similar to how FDNY squads work where for some calls the squad runs behind the engine piece, min 1 max 2, maybe have some sort of specialized training like heavy machinery operating or something)
I want to point out that this would be good to add for mission variations and have later game missions require the units outright. The same way that some missions require a fire investigator and it has a variation where it doesn't, but when you buy the fire investigation office or extension, those missions can spawn.