Fuel MPG

My 2016 5.7L running 80 MPH on the freeway with Cruise set is running about 2400 RPM getting about 14.8/15 MPG
My friend just purchased a 2019 Ted Crewmax 5.7L . I had the opportunity to go on trip to Idaho Falls from our home in Boise, Idaho. My friend let drive his truck because he had told me that he was getting ( 19 MPG )
On the Freeway with Cruise set at
80 MPH .
With the Cruise set at 80mph his 2019 was running only ( 1400 RPM )
I thought maybe he had an OD that mine doesn't have, but no such thing.
Why the difference in RPM'S on identical Truck's ???

 

Both trucks stock? My '08 when it was all stock would get 17 to 18 on the freeway going 80. Even hit 19 once. Then I got bigger tires and lift and it dropped to 14.

 

My 2019 5.7 DC is getting 18.2 MPG with cruise set @ 69.

 

Did you buy your truck brand new or used. Maybe somebody re-geared the axles. Although I can’t remember, but 2400 RPM at 80 sounds normal. I wonder if it’s possible he got different axle ratio’s. Because 1400 rpm at 80 mph sounds really low.

 

Also you need to be hand calculating both trucks instead of using the display. There can be discrepancies and not every truck is the same. Although most are fairly close I still suggest hand calculating.

 

Probably because one of you has "Super White", and the other has "Midnight Black" or some other color??

 

My 2019 CM runs 2K RPM at 74-75 mph in 6th gear with stock tires/ 275/55R20/ 31.9" diameter/ 100.2" circumference. The math works out. According to the gearing specs found here on page 2, the numbers work out. 6th gear is .59 and the 5.7 tow package rear diff is 4.3. At 2,000 RPM in 6th gear, the axle is rotating 788.3 times a minute (2,000/.59/4.3). Works out to 74.8 mph.

 

Agreed. I’ve experienced this with my 2019 when i hand jam.

 

Another mpg thread?

You must have flat terrain. Rolling hills here and with cruise set to 80 I'm at 14mpg

Hmm, another gas mileage thread.

I'm skeptical that a stock 5.7 can run 80 mph at 1400 rpm over rolling hills without downshifting while getting 19 mpg.

Mine runs about 2100 rpm at 80 and already has downshift to 5th or 4th to get over the rolling hills.

 

Southern Idaho freeway's does have some elevation change's but we have sections that are flat for upward's of 80 to 200+ miles.
And yes both truck's do down Shift on the grade changes. The 2019's RPM increase's just like my 2016.
I'm wondering if there might be a Computer adjustment that could be made for changing the RPM

 

Hand calculated gas mileage?

 

I seriously doubt 1400 RPM at 80 mph