The official record attempt was closely monitored by Guinness World Records, adhering to its strict rules and documentation procedures. On its efficiency-focused August 23 and 24, 2021 journey, the Mirai logged an impressive 152 MPGe (higher than any other EV) with water as its only emission. Guinness World Records adjudicator, Michael Empric, validated the Mirai’s tank with a seal at both the beginning and end of the journey.

Driven by professional hypermiler, Wayne Gerdes and co-piloted by Bob Winger, the two-day trip began on Monday, August 23, 2021, at the Toyota Technical Center (TTC) in Gardena, California, home of Toyota’s fuel cell development group. The duo traveled south to San Ysidro and then north to Santa Barbara cruising through Santa Monica and Malibu beach along the Pacific Coast Highway. They returned to TTC that evening and logged 473 miles (761.22 kilometers) with only two driver swaps that day.

The next day, August 24, 2021, consisted of more local driving loops, where they pushed through 372 more miles (598.676 kilometers) of morning and afternoon rush hour traffic on the San Diego freeway between Los Angeles and Orange County until the Mirai had no more hydrogen left and coasted into TTC with a grand total of 845 miles (1,359.9 kilometers) driven, as witnessed by Empric.

By the end of the trip, the Mirai consumed a total of 5.65 kilograms of hydrogen and passed a total of 12 hydrogen stations along the drive routes without refueling. The Mirai was driven mainly during rush hour traffic in temperatures between 65 to 83 degrees Fahrenheit (18 to 28 degrees Celsius). It emitted zero pounds of CO2, where a standard internal combustion engine vehicle would have emitted about 301 kilograms of CO2 over the same distance.