> We'll have to stop equating cars with smog. Modern cars don't have exhaust pipes. So this can no longer serve as an argument against cars in general.

But:

> Data from the UK National Atmospheric Emissions Inventory indicate that particles from brake wear, tyre wear and road surface wear currently constitute 60% and 73% (by mass), respectively, of primary PM2.5 and PM10 emissions from road transport, and will become more dominant in the future.

In terms of local air quality, this will remain significant (tyre/road wear will get worse unless we manage to significantly reduce the weight of electric vehicles), and what little studies have been done tend to suggest this largely negates the gains from regenerative braking.

Essentially, we've _already_ substantially got rid of exhaust pipe smog such that other components create the majority.