If you're in love with this truck, buy it! Expect 10-12 around town and 17-22 on a long trip. But, wait a minute. How heavy is your foot? What is your loaded weight? Are you towing? Towing what? How much do you pay for fuel? Is the fuel of excellent quality? How about the tires? Tire air pressure? Etc., etc., etc............................... This is an engineering forum. I assume you're an engineer. You must know that you have to define all the variables to get a definitive answer. Yes? Sorry if I've added to your confusion. You can't get a straight answer to a curved question.

Yes, this is an engineering forum. However, that does not mean it is limited to engineers. You also assume that the post is by an engineer. If you are an engineer, you should know that assumptions are bad practice, and that they often come back to bite you in the ass. The founders and long-term contributors to this forum have fostered an atmosphere of inclusion, tolerance and encouragement. This brings out the best in all contributors. Please join in that spirit, and welcome aboard!

Munky,

You are corect in that making assumptions can come back to bite you in the ass. I greatly appreciate your reply and your encouragement. I am not an engineer and I realize that my question was not as defined as it could have been. Thank you.

For what its worth from someone who owns a '05 Chevy Duramax 3/4-Ton 4x4 w/Banks Big Hoss Bundle, I was averaging about 17/15 hwy/city stock and 19/17 w/Banks while living in So. Cal where I commuted 35mi each way @ altitudes less than 1000', half hwy/half street. Its changed some in AZ at higher altitudes (3500') and 6mi each way to about 19/15. With the newer engines, they have been getting better mileage performance, so you expect better than what I've been getting.

I'm not totally sold on the 6.7L Cummins yet, considering the large jump in displacement and little increase in performance. Main change was for emissions. 5.9L was pretty much bullet-proof with no technical bulletins issued since 2001. I would have bought one, but because I planned on boosting the performance and they didn't offer a variable turbo, I chose the Duramax. I have a good friend with a 2001 Dodge Cummins 1-Ton Dually and he gets around 21 Hwy with small modifications (Diablo Sport Puck, Banks Hi-Flow Ram, & a Banks Turbo Housing for increasing air volume in the Holset Turbo).

There is good issue, I believe in Diesel Power mag, but might be Peterson's 4-Wheel mag, but it shows thems spending $9 & change and getting 31 mph on a 97 Dodge Cummins. One of the main things was running tire pressure at 75psi.

Sonave Sunsets,

Thank you for your reply. This is all very good information.