Mary Barra, G.M.’s chief executive, discussing features on the battery-powered Chevrolet Bolt in January 2016. G.M. said it would introduce two new all-electric models within 18 months as part of a broader goal to create an emissions-free fleet. DETROIT — In a push to produce cars powered by batteries or fuel cells, General Motors on Monday laid out a strategy to vastly expand the number of electric models in the marketplace. G.M. said it would introduce two new all-electric models within 18 months as part of a broader plan toward what the company says is its ultimate goal of an emissions-free fleet. The two models will be the first of at least 20 new all-electric vehicles that G.M. plans to bring out by 2023. The announcement came a day before a long-scheduled investor presentation by Ford Motor that was also expected to emphasize electric models. After the G.M. news […]