: Use a "Mod Installer" program. You point it to the mod file and the game folder, and it handles the rest. Manual : Extract the .rar file.
If you are looking for a reliable way to download and manage the game or its components, 1. Official Game Download
Open data\config\player_cars.xml in Notepad and paste the text snippet (often found in the accompanying .txt file) before the final tag.
: You can download the setup file (approx. 2 GB) directly from the City Car Driving Download Page . They provide mirrors and torrent files for faster loading.