First off, great site!! There's a lot of great info for a first time Cummins buyer like myself. This will be my first diesel vehicle, and I am just wondering about the fuel economy. I will be getting a 2500 Mega Cab 4x4. I am not sure which motor to get though (5.9 vs 6.7). I don't tow heavy equipment. I put a lot of miles on a vehicle. I plan on adding a leveling kit and 33" or 35" tires. Also, I will change the air filter. Which motor should I go with for the best fuel economy, and what MPG can I expect with this configuration? I apologize if this was covered in a different post. Thanks in advance for all your help.

Craig

 

I have 5.9 with 35inch tires, no programer or chip. I get 15.5 religiously with a heavy foot.

 

I can't speak to the 6.7 but from what I've read about it here and other forums it does not do as well as the 5.9. That said, my 5.9 gets about 18 on the interstate and even with some mixed driving city / highway. I really don't have any all city driving around here. My best was 20 and my worst towing my 8500 lb camper has been 9. Life time average including towing and every type of driving I've dome is right at 17. BTW I have 35K miles on my truck.

 

There are guys at working reporting 24mpg in 2x4 with altered intakes, silence ringsremoved, and aftermarket air filters. Both have over 40K miles. Is this fact or fiction?

 

The 5.9L probably does get better fuel economy. I get about 15 MPG, although mine is far from broken-in. I expect it to get a little better.

 

fiction. . .the last trucks to venture into the 20's en-mass were the 03 and 04 305 engines. the 12 valve engines routenely went into the mid 20's stock. after 04.5 mileage has been the high teens at best with a few here and there getting about 20.

even under the best combination, auto, 3.73's 2wd reg cab. . .with the 6.7L I would only expect 18-19 tops after a good breakin. just remember, it take fuel to make power. the more power you produce the more fuel you have to use to make said power.

 

Drew, I must be exceptionally lucky.

06 5.9 6 speed manual 4x4 quad cab and I average between 20-21. I have hit 22.5 on a good day. 60k miles and half my driving is 75-80mph and the other half is 65-70 with only minimal slow speed. But, I did only start seeing these numbers after I reached 25-30k miles on the clock. Wasn't bad before that (except right off the lot) but definately took a while to get there.

Of course, these numbers are assuming I DON'T let the wife drive it
I can fillup, let her drive less than 5 miles and I'll only hit 17 on that tank. Never did figure that one out.

And, yes, all my numbers are hand calculated. I don't have those fancy readouts in my truck.

 

I have been getting great MPG, my best was around 22.7 MPG. I live in the country and there is not any stop and go type driving at all. Although I avg in the high teens, when I make a trip to the city and back if I keep it in the 65mph range I can get 20-22mpg. This is all hand calculated, I am just getting ready to hit 2k miles. I am not even close to being broke in so I am pretty happy about my mpg so far. I am also bone stock right now and when I do get that kind of mpg I know that it is because I have been driving with a very light foot.

So for me this far it has been,

long trip to the city around 22mpg
Light foot driving in my town around 17-19mpg
and normal driving when I have a little fun has been around 15-16mpg.

 

yes. . .there are a few in the crowd that rea able to hit those numbers. . .and it is hit or miss and when you do have one that is able to get those numbers it has to be a good feeling.

 

Well, I certainly don't complain about it

And, it is fun to remind Mayfair of it once in a while