I’m far from an expert on current Parisian politics, but I can confirm that the mayor of Paris doesn’t preside over a lot of suburban area. Not sure for the power of the mayors of the individual arrondissements.

The (populated) area inside the red line is basically all high density so the people actually doing the voting should be rather in favour of fewer cars and better transit. The surrounding suburbs — where there are more carbrains — are different administrative units so they don’t really have a say in how central Paris is run.

In many areas (e.g. Toronto), these suburbs also vote for the mayor and tend to block progress. I think this is also part of how Paris can make rapid progress— the voters actually live in the city proper.