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25.8 MPG! 2016 GMC Sierra ROUND TRIP - 463.9 miles

SouthwestORV

By SouthwestORV
in Engines & Drivetrain

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truckguy82 Senior Enthusiast

truckguy82

Posted
Posted
25 minutes ago, Grumpy Bear said:

I wasn't being sarcastic. Your basis of comparison was 70 mph and it isn't anymore active at that speed. It can't be less active than zero. That not sarcasm. That's a fact. This systems sweet spot is 50-55 mph. IF you see it come on at 70 mph bet you have a downhill and fuel is zero. I has no effect. At speeds such as your driving it can't help you. Not won't, can't. 

 

 Yea....:bs: they might make those comments but I'll take their money. 

 

KARNUT is not a speed freak but he isn't bashful either. He drives above the systems optimal limit enough that it doesn't have much effect. So what he is saying is the "Within the references of his personal driving style" he doesn't see much difference.  

 

BINGO!

Flat road in the summer, with AC, my afm is definitely on at 70mph. It will switch back to v8 on a slight incline, but if it’s flat, v4. Since I don’t have a level in my truck to monitor the slope, I’d say v4 is on like 90% of time with cruise set on 70mph. In the winter 65mph will do that.


one would assume a 6.2 has a higher hp output threshold in v4 mode

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JB45 Enthusiast

JB45

Posted
Posted
24 minutes ago, SouthwestORV said:

I would expect better too...hmm. Several thoughts, based on personal experience:

1. I'm running 91 Octane fuel. You?

2. I run my tires above 34psi = less rolling resistance. 

3. I've noticed that the fuel economy drops drastically as speed increases. At 75mph my truck is getting about 21mpg.

4. Yes, my truck is 2wd so there is less weight, and less energy loss because it isn't turning/hauling all of the 4wd components.

5. My truck is also lighter because it's a regular cab, even if the wheelbase is similar. 

6. I do run 0w-20 Mobile 1 Synthetic oil in the truck, and follow the recommended service intervals on the display. 

7. Running the way I do, my truck spends a LOT of time in "V4" mode. Yet, only the slightest throttle increase bumps it back to V8. So I imagine the larger/heavier all season tires on your truck, plus the added weight and parasitic losses from 4wd simply require more effort to haul around.    

I run 87, that could be the key difference if everyone reporting the 22+ numbers are running 91. I figured most guys run 87, but that might not be the case!

 

I like to run mine at 35psi, they are only at 30 because I haven't gotten around to it. 

 

If I could get just 18 mpg running 75 I would be extremely happy. Definitely not expecting amazing fuel mileage driving over the speed limit, but I also don't see why it's so low. Watching the tac from 75-80 there's only about a 200rpm difference on somewhat flat ground. 

 

That's what I'm going to start running in my truck, 0w-20 mobile 1 synthetic. Very curious to see if that makes much difference, I feel like it will. 

 

I notice that when I'm in v4 mode, the engine struggles to maintain speed at the slightest of grades. One tank I specifically wouldn't give extra throttle just to see how far it would slow down before downshifting or reactivating v8. Even by driving like this I wasn't breaking 15.5. 

JB45 Enthusiast

JB45

Posted
Posted
30 minutes ago, SouthwestORV said:

It is funny that you got better MPG going 80 than 70 - I wonder what the factor was - could have been headwind. I agree that you should be getting better. I work with a plumber that drives the very truck you own, and he said he gets 18mpg on the road (with his plumbers racks, etc.) 

Like I said, nasty storm. I did get the truck the same day so maybe I was more lead footed on take-offs. But that's really getting down in the weeds on the 70-80 comparison. My basic thoughts were I was getting poor mileage even for the driving circumstances. 

SouthwestORV Enthusiast

SouthwestORV

Posted
  • Author
Posted
5 minutes ago, JB45 said:

Like I said, nasty storm. I did get the truck the same day so maybe I was more lead footed on take-offs. But that's really getting down in the weeds on the 70-80 comparison. My basic thoughts were I was getting poor mileage even for the driving circumstances. 

I agree - I don’t see anyone else reporting your low numbers. Did you buy it used? Perhaps that’s why they sold it?

JB45 Enthusiast

JB45

Posted
Posted
45 minutes ago, Grumpy Bear said:

I wasn't being sarcastic. Your basis of comparison was 70 mph and it isn't anymore active at that speed. It can't be less active than zero. That not sarcasm. That's a fact. This systems sweet spot is 50-55 mph. IF you see it come on at 70 mph bet you have a downhill and fuel is zero. I has no effect. At speeds such as your driving it can't help you. Not won't, can't. 

 

 Yea....:bs: they might make those comments but I'll take their money. 

 

KARNUT is not a speed freak but he isn't bashful either. He drives above the systems optimal limit enough that it doesn't have much effect. So what he is saying is the "Within the references of his personal driving style" he doesn't see much difference.  

 

BINGO!

And I also said for my personal application I don't see the benefits.

Sounds like him and I drive similiarly. And he was getting much better fuel mileage. Almost 10 mpg. With and without AFM. 

JB45 Enthusiast

JB45

Posted
Posted
11 minutes ago, SouthwestORV said:

I agree - I don’t see anyone else reporting your low numbers. Did you buy it used? Perhaps that’s why they sold it?

Yes, it's used. It only had 22,000 on it when I got it the beginning of this month though. Pretty new truck to me! 

SouthwestORV Enthusiast

SouthwestORV

Posted
  • Author
Posted
10 minutes ago, JB45 said:

Yes, it's used. It only had 22,000 on it when I got it the beginning of this month though. Pretty new truck to me! 

I started driving this truck (original post) a little over two years ago. It had 6000 miles on it. It was a U haul rental truck.  

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

2016 Silverado Crew Cab 4X4, 5.3/6L80e with 3.42 gears. Runs 89 octane, 35-40psi in the tires, front is lowered 1.5in, rear is lowered 3in. It's tuned with HP Tuners by me with no AFM/DoD active and doing 65-70mph it has no problem getting 22-24mpg avg on the open road. Draft a semi truck and 26-27 was the best I got over a 50 mile stretch.

 

City mpg, 10-14 lol.

JB45 Enthusiast

JB45

Posted
Posted
1 hour ago, SouthwestORV said:

I started driving this truck (original post) a little over two years ago. It had 6000 miles on it. It was a U haul rental truck.  

Nice. I thought it looked a little like one, but I bet it makes a good driver!

JB45 Enthusiast

JB45

Posted
Posted
59 minutes ago, CamGTP said:

2016 Silverado Crew Cab 4X4, 5.3/6L80e with 3.42 gears. Runs 89 octane, 35-40psi in the tires, front is lowered 1.5in, rear is lowered 3in. It's tuned with HP Tuners by me with no AFM/DoD active and doing 65-70mph it has no problem getting 22-24mpg avg on the open road. Draft a semi truck and 26-27 was the best I got over a 50 mile stretch.

 

City mpg, 10-14 lol.

I bet your truck has a nice street stance to it. I never thought that I'd like the look of these trucks sitting lower but I gotta say they look pretty good. Still probably going to level mine. 

 

How did you like tuning yours with HP tuners? Any TCM tuning? Seems like the AFM/DoD delete is pretty straight forward but doing anything extra makes me a little nervous. 

SouthwestORV Enthusiast

SouthwestORV

Posted
  • Author
Posted
1 hour ago, CamGTP said:

2016 Silverado Crew Cab 4X4, 5.3/6L80e with 3.42 gears. Runs 89 octane, 35-40psi in the tires, front is lowered 1.5in, rear is lowered 3in. It's tuned with HP Tuners by me with no AFM/DoD active and doing 65-70mph it has no problem getting 22-24mpg avg on the open road. Draft a semi truck and 26-27 was the best I got over a 50 mile stretch.

 

City mpg, 10-14 lol.

Awesome! I've done this - drafting semis does make a big jump in MPG's. Does yours run even stronger with the tune? 

SouthwestORV Enthusiast

SouthwestORV

Posted
  • Author
Posted
18 minutes ago, JB45 said:

Nice. I thought it looked a little like one, but I bet it makes a good driver!

It does! Base model doesn't mean much anymore. This pickup doesn't feel base at all. The factory stereo syncs with my phone and sounds great. It has cruise control, air conditioning, tilt steering, power mirrors, power windows, chrome trim, nice seats with fold down center console...it's perfect! Feels like a luxury truck compared to other pickups I've used. 

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

I don't have any pictures of it with it being lowered but it's surely feels lower and there is a pretty big height difference when driving next to or parking next to a stock ride height truck. I prefer this stance as I don't take it offroading or anything. It'll see plenty of dirt roads up around the cabin but that's about it.

 

I've had HP Tuners since 2012 so I've been around it long enough to not have many worries when messing with it. I've done many changes to the calibration from the engine side to transmission tuning. Changes to the transmission make a huge difference in everyday driving to me. No more 6th gear by 40mph type stuff so it actually drives like you think it should. I've even plumbed and wired up a flex fuel sensor for E85 fuels, it's a small bump in performance just running that fuel with a dialed in tune.

Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
4 hours ago, SouthwestORV said:

I believe it! Last September I drove from Marysvale Utah to Taylor, AZ with a dirt bike in the bed of my 2016 Sierra 5.3. It was a Sunday morning, so I took my sweet time and cruised 55mph the entire way. By the time I hit Page it said 30MPG! When I filled up in Page the "distance to empty" said "999 miles". When I calculated manually, I was in fact doing 30mpg. But I rarely share that experience because people roll their eyes. 

Let them roll their eyes. They don't pay your bills. 

JB45 Enthusiast

JB45

Posted
Posted
2 hours ago, SouthwestORV said:

It does! Base model doesn't mean much anymore. This pickup doesn't feel base at all. The factory stereo syncs with my phone and sounds great. It has cruise control, air conditioning, tilt steering, power mirrors, power windows, chrome trim, nice seats with fold down center console...it's perfect! Feels like a luxury truck compared to other pickups I've used. 

Mine is the base model too and I love it. 4wd shifter on the floor and same thing with the radio. I stream Spotify 90% of the time when I'm driving so the automatic sync is so handy. Those automatic power down and up feels like revolutionary technology to me. Haha. My truck that I traded in was a 04 chevy 2500hd single cab 6.0 with a 5 speed standard transmission. Crank windows, manual locks etc. Loved the simplicity, but the old girl just had too many miles to be considered reliable. I know I'll miss that truck eventually but this was the best decision. 

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