i found this in my photos of my RTW (so far)

this is one of my better mileage days, from a full tank start i filled up at 301.3 miles, i put in 4.399 gallons - remember the US gallon is smaller than the UK, the tank holds approx 5.1 UK gallons or 6.1 US gallons so the theoretical range was 417.81 miles to the tank