Floor It

At $3 a gallon, Americans just grin and bear it, suck it up, and — while complaining profusely — keep driving like crazy. At $4, it is a world transformed. Americans become rational creatures. Mass transit ridership is at a 50-year high. Driving is down 4 percent. (Any U.S. decline is something close to a miracle.) Hybrids and compacts are flying off the lots. SUV sales are in free fall.