Meanwhile, the feds' fuel-economy administrators are currently operating at a dead run trying to keep up with a host of new, highly digitized fuel-saving technologies, such as "Eco" throttle mapping and stop-start (the engine cuts out as the vehicle coasts or stops), which were practically invented to hack the EPA testing cycle.
WSJ: 2013 Ford C-Max Hybrid Review: A Fine Car Falls Way Short on MPG | Rumble Seat by Dan Neil