John and Helen Taylor are the two of the world's most fuel-efficient drivers, and to prove it they've set off on an 8,000-mile drive around the United States to set a new record for fuel economy.

The husband-and-wife team from Australia are the Lennon and McCartney of hypermiling, having racked up three-dozen fuel efficiency records in 26 years. They've already circumnavigated the globe on a record-setting 24 tanks of fuel and crossed Australia on just eight, getting 75 mpg along the way. Now they plan to go coast-to-coast across America using no more than 12 tanks to beat the current cross-country fuel economy record of 51.8 mpg.

"It will be a great adventure to drive through the 48 U.S. mainland states," Helen Taylor says. "We want to educate the American public that by choosing the right car, using the right fuel and adopting fuel-saving techniques, everyone in the U.S. can save money, fuel and reduce carbon emissions."

The pair set off from Chantilly, Virginia this morning in a new Volkswagen Jetta TDI. The EPA rates the car at 29 city/40 highway, but VW says independent tests by AMCI returned 38 city/44 highway. The Taylors believe they can improve that by avoiding sudden starts and stops, scrupulously following the speed limit, keeping their tires properly inflated and following other basic "fuel-stretch" techniques anyone can adopt.

The trip will take the couple counter-clockwise around the country with stops in Vermont, Ohio, Iowa, South Dakota, Montana, Nevada, California, Colorado, Oklahoma, Illinois and Louisiana. They expect to arrive in West Virginia on Sept. 26.

Topping the record should be a piece of cake. The couple averaged 75 mpg earlier this year during a 25-day, 9,060-mile trek around Australia in a Peugeot 308 diesel. Two years ago they set the Guinness world record for fuel efficiency for a 'round-the-world trip, slogging 18,467 miles through 25 countries in a Volkswagen Golf diesel that got 52.1 mpg. A hardcore hypermiler on over-inflated tires could probably pulse-and-glide their way to better numbers, but until Guinness recognizes them for it, the Taylors hold the title.

You can follow their progress at FuelAcademy.org.

Photo by Volkswagen.