Anyone who had bought there truck new, how many miles did you have on the clock until you noticed an improvement in fuel Mileage?

 

My truck didn't hit a magical number and start doing better. I had a slow steady improvement over the first 10K miles, then leveled out for a while then started back up again in the 40K range and leveled out in the late 50's. I am hoping to get a little bit better but probably have hit the top.

 

What is your highway mileage now?

 

Well state highway 65 and less I get 20mpg. Interstate highway 70+ it drops off to around 18.

 

Pretty good as far as these trucks go. But I do have the DPF so I should expect about 18 at 65 MPH. I will stay at 65 the whole way next month and let yall know whats up. I am driving from texas to Minnesota, then back to Texas with my bronco in tow, then to Arizona and back.

 

20k was when things leveled out for me. . .but since the 315's things have been. . .well. . .'interesting'

ran from my house to dorchester SC and back(about 600 miles) doing 70-75mph and averaged 18.2mpg(smarty on #2 and TST on 2/1)

when I had my stockers my mileage was usualy around 17.7. . . and that was doing 70. . .I dunno what gives.

 

The taller tire gives us an advantage. We have a higher final drive ratio, so our RPM's are lower. At 65 MPH my RPM's were 2000 with stock tires. Now at 65 MPH, my RPM's are 1800. Usually a bigger tire hurts all around mileage, but our high torque engines don't even feel the extra rubber. The torque range on my 6.7 is 650 ft lbs from 1500 RPM-around 2350 RPM or something like that. It is flat all the way across the range. Crazy. It is the around town that hurts our mileage. So, maybe if I had the 4.11 gears, I could run a 40 inch tire and get 25 MPG! YEAH!!! kidding.

 

my stocker 265's would run 62mph at 2000rpm, now at 2K with my 315's I'm running at 68mph. lower engine RPM thus not having to fuel the extra RPM's.

the only downside is I cant use 3rd gear to start off like I used to.


edit: BTW, I have 4.10's and a .72 6th gear.

 

my 6.7 saw improvments after 22,000 miles and every tank is getting a little better

 

I just completed a 900 mile trip pulling a 30' camper that weighed around 6,000 lbs through relatively flat terrain (Florida to South Carolina & back)andaveraged 10.25 mpg [:'(]. I have 28k on the odometer.

Oh yeah I forgot to mention I had the cruise set on 65. That was pretty painful. Speed limit on I-95 is 70. Grandmas driving semi's were passing me!!