My wife & I moved this past summer (2012) since I got out the Army a few years ago, while she was being discharged from the Air Force. While the household goods shipment made it's way from Anchorage down to Olympia, Washington, I drove the truck with her & our 2 dogs from Anchorage up to Dawson City in the Yukon, then down to Olympia for a total of 2,989 miles in 6 days.
On one leg of the trip we drove from Skagway, Alaska to stay the night in Fort Nelson, British Columbia. It was on the Alaska Highway (Route 97) when it was getting into the evening, we hadn't eaten, & I didn't think we could make it on what was left in the fuel tank. We stopped in at Muncho Lake where there's a nice fuel-up station/restaurant/motel/gift shop, filled up, ate, & took off toward Fort Nelson.
The next morning in Fort Nelson we filled up before we took off again. From filling up at Muncho Lake to the fill up at Fort Nelson, we drove 156.9 miles on 5.37 gallons of diesel, 29.2 mpg.
Not possible, I thought at first. But when I looked back, it was mostly downhill coasting with a nice flat stretch of road at the end of the trip. We went from an elevation of 2,690ft down to 1,350ft.
By far the best mpg reading for me yet.