well, I have two things on mind, flying military vehicles and 1.14.4 but hey, you've made a great job in this project, most of those the I know like flans or MCheli are just abandoned and it's great to have one that is active. 

In 1.12.2, latest, firing guns causes, and the gun doesn't fire. On tanks, it kicks the player but doesn't crash the server.
[13:51:17] [Server thread/FATAL] [minecraft/MinecraftServer]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_221]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_221]
at net.minecraft.util.Util.func_181617_a(SourceFile:47) [h.class:?]
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:723) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:397) [nz.class:?]
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_221]
Caused by: java.lang.NullPointerException
at minecrafttransportsimulator.vehicles.parts.APartGun.interactPart(APartGun.java:68) ~[APartGun.class:?]
at minecrafttransportsimulator.packets.vehicles.PacketVehicleInteract$Handler$1.run(PacketVehicleInteract.java:81) ~[PacketVehicleInteract$Handler$1.class:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_221]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_221]
at net.minecraft.util.Util.func_181617_a(SourceFile:46) ~[h.class:?]
... 5 more

When ever I put treads onto a vehicle my game crashes. Any suggestions/ways to fix this?

When using the cicada's or panther's railgun it creats an explosion at the place where the vehicle/turret is standing, even when aiming at the air. Is this a bug or am I doing something wrong?

I really like the vehicles, they have good models and it'd be a pity if their guns could only be used aesthetically.

Also, are (gunned) planes planned? I don't really want to play with flans and the only gunned plane in immersive vehicles I know of is the PZL P11.c from the official vehicle pack. I'd love to have some futuristic planes that could be used for pvp instead of resorting to a WWII plane when all the other equipment from other mods is futuristic.

Cheers!

how do i use the tank i added the engine and the seats a wheels

WHY IT DON'T WORK

also i got the jeep to work but it only go backwards 

In reply to rslive_yt:

 if you look at the controls [not the ones in the esc menu but there is one keybind you have to press to bring them up] and there you can see there are some things that change the gear and if the engine is on or not

This is actually incredible thank you so much for making this, it needs to be more recognized. :D

I forgot to put that I'll tell everyone I know to download it :)

Could traingun ever be operational? You could try mixing in the (iirc) upcoming weapons system from Immersive Vehicles into the cart, although I am not sure it's possible.