You used to be able to change several settings by typing two slashes "//" the setting, and then the value you would like to set it as. //build_mode_shift_speed is an example of such setting you can change. These settings have not been accessible since sometime in the development of the rails.
You can even type // TAB and the game will list the settings but as soon as you select one and hit enter you are met with an unknown command error.
Using tab to auto fill // will also spam the whole list, this should be prevented like the normal admin commands have now.