Driving a green car somewhere is, by definition, greener than driving a non-green car. But driving a green car somewhere is less green than getting a ride from your friend who’s also going to the same place. That’s true no matter how much of a gas guzzler your buddy is driving. Consequently, measures that subsidize the production and use of green vehicles tend to actually not be so green in their overall impact. Consequently, I don’t think Salt Lake City’s plan to exempt green vehicles from parking meter fees is very sound. Parking should cost what it costs, regardless of the greenness of the vehicle.
The best way to reduce gasoline consumption is higher gasoline taxes. On the municipal scale, this isn’t necessarily a very attractive option or necessarily even a legal one. The best thing for Salt Lake City to do would be to revisit their parking ordinance (PDF) and go further toward reducing the overall scale of subsidized parking. They already have a rule on the books allowing developers in certain parts of the city “partial relief” from parking requirements if they meet certain complicated criteria. Why not take those parts of the city and say developers should just build as much or as little parking as the market demands? Even if every vehicle in Utah were an efficient hybrid, providing more parking than a free market would is still pushing gasoline use up.