Audi challenged eight drivers to drive its new 2014 TDI models, including the Audi A6 TDI, Audi A7 TDI, and Audi Q5 TDI, across the U.S., from Torrance, Calif., to Manhattan in New York City, with a limited number of stops for refueling, to test the fuel economy of the automaker’s vehicles.

“Crossing the United States in fewer than 48 hours is a hurdle few have ever contemplated let alone completed,” said Wayne Gerdes, one of the nation’s leading high-mileage driving experts and owner of CleanMPG.com. “To complete that journey while also beating an automobile’s EPA highway fuel economy rating seemed even more impossible.”

For the challenge, Audi set the number of refueling stops to four and tasked the drivers with driving across the U.S. in 48 hours, traveling at normal highway speeds. The driving teams consisted of “hypermilers,” i.e. individuals who specialize in driving techniques that maximize fuel economy, and a number of journalists. The results of the challenge showed that the vehicles were capable of achieving significant fuel economy performance, above and beyond the vehicles’ official EPA ratings, according to Audi.

The Audi A6 TDI achieved 43.561 mpg at an average speed of 62.44 mph. The EPA fuel economy rating is 24 mpg city, 38 mpg highway, 29 mpg combined. The A7 TDI achieved 42.653 mpg at an average speed of 62.17 mph. The EPA fuel economy rating for that model is 24 mpg city, 38 mpg highway, 29 mpg combined driving. The Q5 TDI achieved 38.623 mpg at an average speed of 61.90 mph. The EPA fuel economy rating for the Q5 TDI is 24 mpg city, 31 mpg highway, 27 mpg combined.