Hi!
I would like to suggest that you add the "/mts despawn * time * " command to the mod. This command would work like this: all vehicles in the world that have 0% health would simply disappear from the world in * time * seconds. This would help avoid lags on the servers and even on the client side. Each user can manually set the despawn time, or not enable this function at all (by default, or "/mts despawn 0")
(sry for my english)

I can add this, but it'll be as a config, not a command. Configs are where such timers and settings should be saved. Normally, vehicles should not despawn since you'll lose them, but it's quite possible for me to add this for creative and battle servers. Expect to see this in the next update.

Only vehicles with 0% hp will be despawned, yes?

That is correct.

Addressed in 22.12.0.