I am going to say the record is 1,626 miles on a tank per these folks:
https://www.csmonitor.com/Business/I...ne-tank-of-gas
A little internet research found these husband and wife drivers are the real deal and pros. They have broken some 42 fuel economy world records for driving and gas mileage and have their own Hypermiling school.
Well done!
I will say that the 1626 mile record is now questionable since it was done on a 2012 Passat TDI, that was part of the Diesel gate VW scandal of VW falsifying emissions. If they had to do it again with the legal re-tune on that car it would be much less.
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97 Passat TDI Wagon
Bosio 520 DLC nozzles, chip tune
Mufflerectomy, ALH Injection Pump
317k miles
Scan Gauge II
full belly pan
26 gallon tank