John and Helen Taylor, the world’s most fuel-efficient couple, have set a new world’s record for the farthest distance traveled on a single tank of fuel. The Taylors have lots of experience with this sort of thing; they’re professional “hypermilers” with more than 90 world fuel-economy and vehicle-related records to their credit.

For the attempt they decided on a road trip in the U.S. in a stock, Chattanooga-built 2012 Volkswagen Passat SE with a 2.0-liter TDI four-cylinder diesel and a six-speed manual transmission.

Starting in Houston, Texas, on May 3, the Taylors drove through nine states over the course of three days, ending their journey on May 5 in Sterling, Virginia and setting a new record of 1,626.1 miles on a single tank of diesel fuel. The husband-and-wife team averaged 84.1 miles per gallon. Even with fairly stout prices for diesel, the cost per mile worked out to be 4.6 cents.

Prior to the drive, the speedometer and odometer were calibrated by a state-certified testing station in Houston. Officers from the Houston Police Department oversaw validation of mileage, fuel fill-up, and gas tank sealing at the beginning of the drive. In Sterling, a Loudoun County Sheriff’s Deputy verified completion of the drive and mileage prior to removing the fuel tank seal.

To ensure their experiment was reasonably realistic, the Taylors added 120 pounds of luggage and did most of their driving during daytime. They took turns driving and kept each day’s drive under 14 hours.

“We’re excited to have broken the record for the longest distance driven on one-tank of fuel,” said John Taylor. “The Passat TDI was the perfect car for the trip. It offers plenty of interior and cargo space, yet is frugal enough to help us achieve this record.”

The previous record was 1526.6 miles and was also set with a Passat: a European model equipped with a 1.6-liter diesel.

The Taylors have made a career out of driving efficiently and conducting workshops globally on fuel-efficient driving techniques.