truck lua object

Well, it looks like there is no (good) chance to calculate "RPM-ish" value.
We can get Angular velocity from wheel(s), we can get current gear, but what is needed is Gear optimal angular velocity. And that is defined in truck's XML. And because it is "starting point" for game's calculation, it wasn't needed check that value on this side - it is not passed to LUA.
Unless I think up some way, how to "find proper file, find value in that file based on current gear" I am in dead end...