need a well experienced driver to answer this

Speed limit in Texas is 70-75. I'm not raging against that, I'm saying that speed is only a small factor. And also you should not be going over the speed limit.
Tucson to Memphis is about 1400 miles. Perfect for a 2 day job. 65mph is enough to do the job for that.

Sorry to 2saint for going off on a tangent.

When (if) I buy a truck, it will be 2002 or older, 12.7L Detroit because they don't have EGR valves and they get better fuel mileage from what I've read.
I drive a 2007 FLR with a 14L Detroit and I get 6.4 loaded with 20k. Empty I can get close to 7, unless I'm driving into a headwind and then it drastically goes down. I was getting 5.6 mpg between Detroit and Effingham, empty, because of the wind. That's about all I can help you with as far as your question goes.

 

Using the math allready posted here, driving 60 vs. 70 saves you $25.00 in fuel. driving 70 vs. 60 gets you aprox. 30 miles farther down the road,@$1.00 a mile(just to make the math easy)Your $5.00 a day ahead to drive 70, (I'm not taking either side I'm just sayin'...)

 

you drive an average of 700 miles a day which if you are solo with e logs you can legally get over 4000 miles a week with a restart. @ 1 dollar a mike. Is 4000 a week. Now that's why we are out here it make money. I can sit at home where I want to sit anyway. Everyone has there own style. I just want to make as much as possible than go home.I hate nasty truck stops. Unfortunately I stay out 3 weeks at a time so I have to restart at them anyway. Drive the speed limit and you'll b safe and make money too.

 

are you asking what mpg i get?

In a sense lower mile trucks can get higher mpg,,, engine wear creates blow by and blow by is lost energy to the drives making the engine work harder to maintain a set speed/pull.

 

2009 or 2010 Cascadia DD15 engine with app 500 k miles. That would be a good deal....2008 Cascadias have a bad reputation though

 

For fuel economy I would look at the motor. ISX Cummins is a good choice for fuel economy so is the C16 Cat. The other thing that affects the fuel economy is horsepower. Running your horsepower on the higher end of the engine horsepower rating rather than the lower end will usually net you better fuel economy. The lower the rear end ratio the more power, so the less the truck has to work to produce the same amount of power. Taller tires will get better fuel economy, so 11R's will get somewhat better than a low pro and 24's will get a bit better than 22's, but I don't think that that will make that much of a difference in the long run. Volvo's are light and aerodynamic as are freightliners and Internationals (Prostars and Lonestars). But the motor makes a much bigger difference than the brand of truck. Also there will be some difference in fuel economy whether you get an automatic or a manual. The miles on the motor don't make the difference. You also have the option of adding stuff on the truck later, like micro blue bearings, a prefilter for the fuel and add additives to the fuel, little things that will really affect the fuel economy.

 

http://www.truckpaper.com/listingsdetail/detail.aspx?OHID=4055071

Looks like a retired Prime truck, but the price is close enough to argue about.

 

Only thing that I saw that I didn't like was the fixed 5th wheel. Other then that it looks good .

 

I seen TWO 09 Cascadias low miles in Houston for $46,000-48,000

 

Next truck I buy will be a classic truck I'm gonna love to drive but drive slower. I had my share of constant 78mph