If I fill mine to the brim then take my normal journey from Cambridgshire up the A17 (50 to 60mph), A1 (80ish mph), M62 (80 to 90), M61, M6, M55 (80 to 95) the one way trip is around 220 miles. I normally return the next day at the same sorts of speeds and then spend the rest of the week on journeys of about 60 miles a day. I expect the low fuel light to come on between 610 to 645 miles. I try to tank up soon after that but have run for 55 miles before filling. This could be down to running in; 300 miles @ 2300 rpm, 300 miles @ 2500 rpm, 300 miles @ 2800rpm, 300 miles @ 3100rpm and build up slowley from there.