There's a somewhat practical solution. A host computer and some client computers. The host's CPU have to be very beefy, it calculate physics of ALL vehicles. The client computers upload players' input such as vehicle selection, game controller. and download vehicle's situation. The clients' CPUs and GPUs only have to render the downloaded data to display(consume less processing power than single player)
Problem of multiplayer is said to be bandwidth required. Latency of inputs and bandwidth required from host might be more than is tolerable or possible. Even NASA would envy a setup required to host multiplayer game.
No offence, just a some what explanation. I don't think the required bandwidth is that high. The input is the same as other racing simulator. The output is just one more thing: damage appearance. No physics data is transferred through the net. The vehicle state (vehicle.save.json) is less than 60KB when compressed. So only 3.2MB/s is required when updating at 60Hz, Since the client only do rendering, update faster than 60Hz is meaningless. This works if the player doesn't view other vehicles, so other vehicles' state is transferred to THIS client at very very low LOD. If all vehicle's full LOD save.json is transffered and updated, it's only playable via LAN.
