website for tow vehicles mpg by make and engine.

The hitchanything numbers appear to be a non-random survey of people who turned in reports. There are no numbers given telling sample size and no methodology listed. As a former statistician, this makes me cringe. It's kind of like the Kinsey study where men reported their own sizes instead of researchers using a tape measure.

Hitchanything's write up it a pure crock of lying manure. EVERY independent test done over the last 8+ years has shown much different mpg results for the diesels. The GM 6.6L has consistantly had the best mpg's and nearly all were sanctioned tests of all three of the Big 3 diesels offered in each year in like truck configurations pulling the same exact trailers/loads on the same roads and grades at the very same time so wind and/or weather conditions etc couldn't alter the results.

Funny thing is, I DON'T CARE what kind of mileage I get. If I wanted good mileage, I'd buy a Prius. Towing a 3 ton trailer loaded with fun for the weekend is priceless.

Some interesting results! I just assumed everyone is getting ten miles to the gallon better than me? After the new vrs old thread last week!

I use fuelly.com for any auto comparison including recent purchases for DW and my grand-daughter. It doesn't have towing specific mpgs, but it provides some insight into year-to-year changes and brand differences. A quick glance at the big three diesel numbers shows Ford at 15.7 mpg for 2011 with 500k miles driven, Dodge at 14.1 mpg for 2012 with 700k miles driven and Chevy at 16.3 mpg for 2011 with 200k miles driven. All three are 3/4 ton diesel pickups.

HERE is a site where real-world users submit their mileage by specific year, make, model, engine & fuel type. And, you can join and contribute.

Since FE ratings aren't released by manufacturers of HD vehicles and the specs they give for the Duramax are so off base, I don't trust anything in there.

JMO,
Scott