For decades cars have used a hydraulic pump driven by the engine to provide power steering. But at highway speeds the pump draws maximum energy from the engine--just when power assist isn't needed.
Now, says Mike Richardson, chief technology at Nexteer Automotive, the auto industry is quickly converting to electric pumps that switch on only when you're actually turning the steering wheel. One result: about 4% better fuel economy.
Richardson says about two-thirds of cars sold in the U.S. have electric power steering now, and the proportion is growing.