I think this already AMAZING game could be even better with 4x4 challenges and new Functions. One of the new functions could be toggle able 4x4 and lockable differentials. One thing that would be good for this update would be changeable tire pressures. Agraham10
I think selectable 2wd/4wd is planned, might even be possible in the race update with the new per vehicle lua scripting. Same goes for lockable differentials. As it stands right now of course you can use the parts system to swap the differentials for locked ones or higher/lower ratio ones and could also use that for swapping wheels to ones of different pressures (as the pressure is specified in JBeam). I think tweakable tuning setups were also planned at some point which would give a better solution to the tyre pressures.
Something that I forgot to mention is that In the upcoming GUI, A map of the differentials and if there locked or not would be great! Also a symbol of wheather you are in 2wd or 4wd.