Well I'm not sure what to say here about NFS World modding, but when using mods on a certain NFS World server, there's a higher chance to get banned. Some launchers replace your files with server's you join because they don't want you to use your modded files. Back in a day I used and played with some car mods I made for NFS World on World Evolved v2 server, but all those replaced existing ones (as there's a smaller chance to get banned, but I'm not sure at all). To be honest, ban for using replace car mods you're playing with, no matter if car attributes/performance is changed or not (while ecar is still the same), is obviously NOT FAIR rule at all! I still wish this rule to be more soft/relaxed like before addon cars (not replaced ones) were a thing.