With cars there are higher energies involved, and things like that tend to grow with square or cube of the energy. I wouldn't be surprised if car was causing orders of magnitude more plastic pollution than a bike per person per mile.

It’s quite intuitive to think about. The entire tread of the tire becomes ground up plastic dust. Cars burn through significantly more KGs of tires in a year than a bicycle.

Thats obvious and goes without saying, but then I didnt state any specific metrics, only that they both casue the same thing even in different amounts