I own and operate a 2008 Toyota Tundra double cab, 5.7 liter I force V-8 engine, 6 speed transmission. Good friend of mine owns and operates a 2003 Dodge Ram quad cab, 5.9 liter Cummin diesel, automatic transmission. Both of us tow 7x16 foot enclosed trailers. Both of us tow in the same area on the same roads. Both of us run the airconditioners while towing and both of us try not to take off from stops like it is a drag race but we do like to keep up with traffic. I am averaging ( all towing the enclosed trailer ) 10.5-11.5 MPG He is averaging 8.5-10.5 MPG under the same conditions. Unloaded and just driving the truck around we get about the same city and highway mpg. Another friend of mine has a 2005 Chevy four door, loaded and with the Duramax/ allision combo. He doesn't tow with it, just drives it around as a daily driver. He averages around 15 mpg. My truck under the same type of driving he is doing would match or exceed his mpg. On cheaper fuel too no less. You may know people that brag about the great mpg their diesels get, but bottom line is to get this great mpg you have to drive 50 mph in the slow lane and leave traffic lights no faster than a kid on a 10 speed would. Not realistic real world driving. I believe the tread has reversed in recent years... Used to be in the late 1980's and 1990's, diesels did get much better milage over gas trucks. Now I believe the tread has reversed, and the diesels are far worse than they used to be and the gassers are better than ever before now. As always, I am sure there will be someone who will post and say that no way will a gas truck get better mpg pulling some ridiculously heavy load... True, I agree. Over 8-10 thousand pounds of weight I would say a diesel starts to hold a advantage over gas, but under that amount I believe you can do better on gasoline and save all kinds of money in the process.