I'm sure this has been brought up before and I know I've seen this on the MissionChief Facebook page but I wanted to bring this back up as I feel that it could be both a great gameplay addition as well as a good money-maker for the development team.
The Fire Vehicle Workshop, a place where players can combine up to say 3 apparatus functions into one. The American Fire Service differs from the European side in that we have more combination vehicles rather than specialized ones. In much of America, Heavy Rescues are less common because Ladder Companies handle vehicle extrication. Being able to pay credits to combine the functions of an Engine, Ladder, and Rescue would benefit a large number of realistic players greatly and I'm sure they wouldn't mind it being locked behind the Captain rank or having a time set on vehicle upgrades. Just in my setup I can think of several vehicles that are 3-in-1s:
Tanker 304 - Engine-Tanker-Rescue
Ladder 11, 1, 4, 27, etc - Engine-Platform-Rescue
Rescue 71 - Rescue-Air-Command
Rescue 128 - Rescue-Air-HazMat
Truck 1019 - Engine-Rescue-Air
The list goes on but I've made my point.
Worldwide Dispatch Services (formerly USND) has numerous players that build realistically and we're constantly struggling to find out how to accurately represent vehicles within the game. I'm certain that with the addition of a system like this coin sales would skyrocket as players scramble to get their fleets right. Not to mention players that don't build realistically also taking advantage of this to further develop their setups.