If SF was really committed to helping the environment, it seems like giving free parking to Smart (or similar) cars (unlimited time at parking meters and no time limits on parking except moving for street cleaning) would be the quickest way to move everyone to green vehicles. I know I'd probably even switch to one if they had that advantage, and I suspect a significant % of the driving population would as well.
It would be interesting to see a ballot measure for this as it would directly pit SF's leaders stated devotion to the environment with their actual desire to extract wealth from it's citizens.
- Steve