When dreaming up new ways to tax cars, please bear in mind that wear on roadways from vehicles is proportional to miles driven times per-axle weight to the fourth power.

A gas tax is already proportional to miles driven times vehicle weight times a fuel efficiency factor.

Congestion, on the other hand, is a more difficult thing. Vehicle length certainly plays a factor, as well as width, acceleration, and braking distance. Number of passengers is an obvious factor. Trip routing efficiency has a role. I really don't expect local legislators to understand the mathematics of traffic. If they don't commission a study by traffic experts, and do exactly what those experts recommend, they might just end up making things worse.

https://en.wikipedia.org/wiki/Braess'_paradox#Traffic

https://en.wikipedia.org/wiki/Traffic_wave