[robocat]

> they would of taxed cars based on volume + mass

Taxing status goods can be paradoxical (Veblen good): if people buy cars to show off their wealth, then many people may still buy large vehicles because they are a symbol of high wealth.

I guess it really depends on what was done with the extra taxes - there are a variety of ways money could be spent to reduce accidents (although the cynic in me says any extra tax wouldn't be used that way).