How about to add Slipstream and Catchup option for server setup. Server host can set these options ON or OFF individually. With Slipstream physics ON player can use slipstream effect to pass the car in front of them. With Catchup option ON the players who are behind the leader will have slightly more power, or slightly more speed or another improvements (of course catchup algorithm should assume players vehicle class, and condition and vehicle damage etc) so they have a chance to catchup the leader and the races will be more intensive, more aggressive with more fun, it will also help newbies or people with low class cars to have more chances to get good place. It would be cool if Catchup will work only up to the slipstream zone so once player have got the zone behind the leader acceptable for slipstream using the Catchup will not work anymore and players now have to use their skill to pass the leader. GTA V race mode is goos example of race where you can set Slipstream and Catchup.
Of course those options should be optional so players and server host have a choice.
Another idea is to show the server setup (amount of laps, track name, times of day, max amount of players, Slipstream ON or OFF, Catchup ON or OFF, allowed car classes, etc) in the lobby screen, maybe somewhere aside the screen like in GTA V so players can see the server setup.