MPG Surprise

[James Beyer]

Hey, did a 52 mile drive each way with a few hills, but mostly straight roads,  then looked at a 20 MPG Surprise.  On the way back home with several stop and go still had 16.2 mpg, not bad for the 6.6l gas with 10 speed.

Later-

[bruceb58]

Do a whole tank and get back! This is not a valid test.

 

16 MPG I can believe because  I have achieved that on I5 in CA going 71 MPH but over hundreds of miles. 

Edited April 4 by bruceb58

[James Beyer]

Hey Bruce, was nice to see what this engine/trans can do under optimal conditions.  Just was shocked by the mpg and had to take a picture.

Later-  

[Chuck FB]

On 4/3/2026 at 5:22 PM, James Beyer said:

Hey, did a 52 mile drive each way with a few hills, but mostly straight roads,  then looked at a 20 MPG Surprise.  On the way back home with several stop and go still had 16.2 mpg, not bad for the 6.6l gas with 10 speed.

Later-

 

What speed were you traveling at during this run and what approximate ambient temp was it. By any chance had you had the engine and transmission warmed up prior to this 100 mile round trip as I find with my truck it sure makes the difference if its already been warmed up and not just engine but also miles put on to have the transmission and diff warmed up. For example I am driving to town from where I farm and using the same drive summary and note the reading when I get to town. Then upon leaving town as the engine was shut down to reset the reading and drive home the fuel mileage creeps up more due to the driveline having already been warmed up.  

[James Beyer]

8 hours ago, Chuck FB said:

 

What speed were you traveling at during this run and what approximate ambient temp was it. By any chance had you had the engine and transmission warmed up prior to this 100 mile round trip as I find with my truck it sure makes the difference if its already been warmed up and not just engine but also miles put on to have the transmission and diff warmed up. For example I am driving to town from where I farm and using the same drive summary and note the reading when I get to town. Then upon leaving town as the engine was shut down to reset the reading and drive home the fuel mileage creeps up more due to the driveline having already been warmed up.  

Hey Chuck, Happy Easter, the truck was started up for about a minute while I put on boots and jacket.  I set the cruise between 58 to 60 depending on traffic, had a few stop lights, and it was about 50 degrees.  Even though it was a short ride of 52 miles one way, it surprised me it did 20 mpg, Later-

Edited April 5 by James Beyer
L

[Pryme]

I did a 300mi drive for Easter weekend and scangauge showed 17.25. It was 17.7 before getting into the city area. I didn’t bother checking hand calc. Didn’t care enough. Ballpark close enough. 

Edited April 5 by Pryme

[James Beyer]

20 hours ago, Pryme said:

I did a 300mi drive for Easter weekend and scangauge showed 17.25. It was 17.7 before getting into the city area. I didn’t bother checking hand calc. Didn’t care enough. Ballpark close enough. 

I hear your Pryme, 17 mpg+ is great compared to my 2000 2500 6.0l getting 12 mpg at best, Later-

 

[Pryme]

57 minutes ago, James Beyer said:

I hear your Pryme, 17 mpg+ is great compared to my 2000 2500 6.0l getting 12 mpg at best, Later-

 

Yeah that’s very true. My return trip was even better! The only metric that’s way off is cost for trip because I haven’t updated the price of gas for awhile. 

Edited April 6 by Pryme

[Mgyselinckjr]

2021 Silverado Z71

5.3 V8 ZERO ACTIVE FUEL MANAGEMENT

3.23 rear end 

MQE 8 speed 

20in wheels @ 39psi 

5w30 oil 

 

91 mile trip 

 

Edited 4 hours ago by Mgyselinckjr