Using "free" serial numbers or cracks from unofficial sources often leads to security risks like malware and usually does not work due to the required online license check. Version 1.5.9! - City Car Driving

This version has the largest library of custom car mods (BMW, Toyota, etc.).

Using "free" serial numbers from the internet often leads to malware or "Activation Error" loops.

Conclusion Serial number 159 of City Car Driving is widely regarded as the best by many in the community because it improves vehicle handling, enhances traffic AI, balances realism with usability, and supports mods and educational use. Its stability and clear feedback mechanisms make it a preferred choice for both learners and experienced sim drivers looking for a reliable, instructive urban driving experience.

Are you trying to for version 1.5.9?