Indeed, if all new cars and light trucks adopted available and emerging gas- saving technologies, the average fuel economy of U.S. cars would surge to 46 mpg, up from today’s 27 mpg. And SUVs could average 40 mpg, up from today’s 21 mpg, according to a recent study prepared in part by John DeCicco, a senior fellow at Environmental Defense, a New York City–based environmental group.