Of course it could be some new steering wheel controls, but if they wanted to keep them secret, why even build them into the RC prototypes? Those buttons aren't necessary for the kind of testing you do on open roads, they could easily be tested indoors.
I think they just want to hide the screen, but were afraid they'd damage it, or the coat wouldn't hold, or something like that.
Hiding the screen probably has something to do with information about the supercharging, or the new UI. Even though I don't understand why they can't just turn the screen off.