I did find this world record:
https://www.csmonitor.com/Business/I...ne-tank-of-gas
It is funny how it says "tank of gas" when clearly this is diesel powered.
Looking at the photo, the car appears unmodified and its sporting pretty big tires to be achieving 84 mpg.
There is nothing in the article about how this 84 mpg was achieved. P&G? Drafting?
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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