Earlier this week, the car industry fawned over the Chevy Volt, which claims to get 230 miles per gallon. Environmentalists and economists will probably both worry about the impact, unless gas prices skyrocket. And that’s what local civil engineer and Forbes magazine reporter Christopher Steiner is banking on. His book, $20 Per Gallon: How the Inevitable Rise in the Price of Gasoline Will Change Our Lives for the Better, lays out exactly that.