I think streetcars are the solution, they can co-exist on downtown streets with cars then have their own lines when there's space. Did you know there used to be a streetcar that ran from Medford Sq. to Stoneham Sq. through the fells?

There's little to be gained by politicians saber-rattling and telling people to not use cars when there are no practical alternatives. If you don't live within the inner 1-2 city ring around Boston and you're not on the commuter rail, you have no choice but to drive.