From Chevrolet to Tesla, Toyota, Hyundai and Volkswagen, automakers around the world are intensifying development of vehicles that use less fuel and pollute less. “Fuel efficiency remains extremely important to car buyers,” Autotrader senior analyst Michelle Krebs said. “About half the people we query have said so for the past year, despite relatively low gas prices.”Prices are falling and practicality is rising. Jaws dropped when Chevrolet revealed a 238-mile range for its new $37,495 Bolt electric car. Chrysler pushes electric vehicles deeper into the mainstream when its Pacifica minivan adds a plug-in hybrid model that promises 30 miles of gasoline-free driving.