A network prototype I started working for a personal project. The game specs required 100 vehicles per server. Thus, using Unity's network solution were not a viable option.
It was implemented on top of Unity's Transport System and with a server authoritative design. Only relevant input keys were sent to server and it responded with a complete world snapshot. Without wheels data, I managed to keep the snapshot for 100 cars below 1500 bytes. Client prediction, server reconciliation and distance-based data quality selection were the next steps to implement. The delay was masked as if it was from the vehicle steering itself.