Business Green: A previously unheralded electric car maker emerged as an unlikely saviour for the US auto industry this week, announcing plans to step in and take over a Toyota factory in Fremont, California when the Japanese car manufacturer vacates the plant at the end of the month, potentially saving 4,700 jobs. Aurica Motors said that when Toyota vacates the NUMMI plant on 31 March it wants to convert the facility to make its planned E-Car — an all-electric vehicle featuring swappable battery …