Hi Gary, The computer seems to recalculate the range and fuel left with reference to the last journey made. The range on my 2.7D s type varies from 490 to circa 550 at times. I filled up last week after a lot of short journeys and it showed 494 miles range. I then drove exactly 50 miles mostly motorway but with a 15 minute traffic jam on the M6/A14 junction. I averaged 48.2 mpg, and the range left was 514, higher by 10 miles then when I started. Curious! Regards, Peter.