to re-sign all modified RPF packages with ArchiveFix (if another child RPF package is nested in an RPF package, you need to take out the nested child package and sign it once, then put it into the parent RPF package and sign the parent RPF package).
be careful not to Modify update.rpf, which means that the Addon-type vehicle mod will not be able to play online, or you can manually extract the model and modify the name, change it to the model name of a car that already exists online, and then replace the file.
because this method is to replace the file and sign the file, it will hardly be detected by the official. At present, R star has not checked the integrity of DLC files, and it is unlikely to do so, because if it is necessary to check the integrity every time it goes online, it will cost too much to read and write the hard disk, and the waiting time will be too long, and it will return to the previous era of watching the cloud, so the first method is recommended.