Electric car tipping point may challenge pioneers

Electric car prototypes and plans are set to dominate the Paris auto show as the Volkswagen diesel scandal and falling battery costs persuade executives and investors that plug-in vehicles are ready to go mainstream. The expected flurry of announcements signals a threat to pioneers of the current generation of battery-powered cars, such as Tesla and Renault-Nissan , who will now have to work harder to defend their lead. VW is leading the charge, keen to turn a page after its exposure last year a