Jan 23, 2014 Most economical cars of 2014. EPAFuel Economy Click tip: The Environmental Protection Agency (EPA) now lists the most fuel efficient cars in the states. The most fuel efficient is GM’s electric Chevrolet Spark EV. epa.gov (Full list), earthtechling.com (Chevy Spark EV) Previous article Volkswagen, Smart, Changan, GM, Renault. Next article Helmut Holzapfel, Elon Musk.