While poking around in the bullettime lua i found some references to fast motion, changing values to allow 2x speed in the lua itself prompts a message saying the game is running faster than real time, but the actual simulation speed does not change, is this limited in the engine itself?
You can run the game at 2x speed or whatever it is. The integrated performance testing does use x2 speed, but to allow the game to use that with key bindings and such you would most likely have to do some lua stuff to add an binding to turn it on. Not sure about physics stability at 2x speed.
I'm sure its possible, but just because its BeamNG I don't think the game would enjoy it. Your computer would probably die.
I've edited the lua to allow for 2x speed, but as far as i can tell, the simulation speed does not change, even if it says it does.
Then how does this: https://www.beamng.com/threads/performance-statistics-feedback-thread.28306/ work? If you use the automated performance testing, the game seems to run at at least 2x speed
This is an unsupported feature. You may attempt to use it; it may or may not work, and it may or may not stop working in the future, so use at your own risk, and don't rely on it. As for how it is used exactly, I am not familiar with it, but @Diamondback may be able to assist.