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KEEP ON RUNNING

While electric hybrid vehicles are becoming increasingly popular in the US, the government’s Environmental Protection Agency thinks they are the wrong type. Most drivers are buying hybrids that work using a “parallel” system. In them the wheels are driven by a battery-powered electric motor, and a conventional fuel-burning engine takes over when the battery charge falls too low. The EPA thinks a “series” system is better, and is patenting a control system for a hybrid in which the wheels are driven by the electric motor powered by a battery that the fuel engine keeps charged up. The trick is to smoothly adjust the…