Ok someone else will call BS on me too, especially since people keep saying that the 2006 6-speeds are doing lousy for mileage.
I got 22. 6 MPG last weekend, and yes that's US gallons, hand calculated. Drove up to Dawson and back, 701. 3 miles and took 119. 34 litres (filled to top of the neck), which is 31. 0284 US gallons.
Last tank was 60% city driving and I got 19 MPG (US).
Of course our speed limits are lower up here, and I made a point of doing the speed limit all they up to Dawson, 56MPH. But it proves that it is possible to get good mileage with my 3500 if I slow down a bit. And since diesel is $. 20 a litre more expensive than Whitehorse I wanted to make sure that I got there and back on one tank of fuel.
Paul