Glad you enjoyed it! And thanks for streaming the project.
The cars were actually fixed, because I didn't have the palette space on the Amiga to provide the diversity having more on screen would require! Technically it would work, but you'd have to reuse existing palettes. So I decided to fix the traffic rate as a result. An awful lot of design decisions were led by the tech limitations on this port.
Could easily do a no-traffic mode though. In fact, it already exists in Cannonball... which I worked on previously, if you have tried that in the past.