Without a doubt Multiplayer. If the devs won't do it, I suppose something like what happened to Euro Truck Simulator 2 Multiplayer will happen.
Proper automatic tranmissions Turbochargers/superchargers that actually appear, perform accuratly, and make sound Damagable environment More detailed engine simulation (ie. damage from over revving and collisions, removable engine parts & effects, correct sounds for number of cylinders, proper diesel engines, etc.) Proper AWD with center differential CVT transmissions Horns & sirens
(Turbo-)superchargers actually appearing is simply a case of JBeaming. Sound and proper simulation, not so straightforward. CVTs are in game already (hirochi sunburst has one via the vehicle lua system)
Other games have turbos so they could do it while supercharging like you said is pretty straight forward. The CVT doesn't really act like one so a properly responding CVT would be what I ment.
aero dynamics are already in the experimental (check out the b25 Mitchell) my dream would be a motor home and a controller configurator that makes input maps for you and boats and planes
Why have there been no tanks and stuff. I know it would clip into everything but just to drive around in.
An oval and 24 online racers - - - Updated - - - What also would be nice : 1 downloadable file with ALL released cars and maps and objects And something else : modifiable exhaust notes - - - Updated - - - Cops, lots of cops.