I remember driving into sf and not being able to see downtown. But really pollution is an issue everywhere. Yes cars are a small drop in the bucket but I want to do my part. I like performance but not at the expense of the environment.I remember growing up in LA County and not being allowed to go out and play at recess due to smog alerts. The air was brownish orange and my lungs hurt. The politics of these policies drive me crazy but there is no doubt that the air quality has greatly improved in just a few decades.