Washington Post: Betting that hybrid and electric vehicles will play a growing role on American highways, General Motors is expected to announce Tuesday a $246 million investment to add production of electric motors at its White Marsh, Md., manufacturing plant. The decision reflects confidence at GM and other automakers that the “electrification” of the U.S. fleet is not far away, with GM officials likening the importance of electric-motor technology to that of engines in gasoline cars. The …