The downside to lower gas prices: people are driving more. Which is why I always say that if you really want to tackle the environmental consequences of automobile gas consumption and emissions, the ONLY way is through higher gas prices. A tax is appropriate in the Pigouvian sense, and is more palatable right now than when gas was $4 a gallon. It will be $4 a gallon again in a year or two, so let's get the tax in now while we can. Go Ted go!