25.8 MPG! 2016 GMC Sierra ROUND TRIP - 463.9 miles

SouthwestORV · January 27, 2020

Hello friends,

I get a kick out of how well my company truck does on fuel. Here's the latest report: (2016 GMC Sierra 1500, 5.3 V8, 2wd, LWB, Reg Cab)

Saturday night I filled up here in Taylor, Arizona (northeastern AZ). Reset the trip odometer before leaving the pump. Drove home and slept. Sunday morning I woke up at 3:30am, left at 4am and drove to Sahuarita Arizona (south of Tucson), a trip of 4.5 hrs. Attended a family event (blessing of a child) and then drove back home 4.5 hours to Taylor, AZ. Drove home, slept the night. Got up this morning, drove back to the fuel station and filled up. My guage showed half a tank remaining. It took 17.977 gallons. Round trip was 463.9 miles according to the trip odometer on the truck. I also verified this mileage to be exactly correct on Mapquest.com - which reported 461 miles, but didn't account for a few little detours along the way. So there it is folks!

25.8 mpg. I'm very happy with that. The MPG display showed 25.0 mpg.

I love this truck. It looks nice, tows well, hauls well...it's quiet and comfortable and a joy to travel in and work out of.

CamGTP · January 27, 2020

Years ago I had a 2006 Sierra 2WD long bed 5.3 work truck and even with 255k miles on the clock it could return 23-24mpg on the freeway in the summer. It had a 35 gallon tank, so I could have gone like 750-800 miles lol.

Nice to see a newer truck get better mileage.

Grumpy Bear · January 28, 2020

Kudo's on your results. Two questions. How fast did you drive ballpark? What wheels are those? NICE!

SouthwestORV · January 28, 2020

5 hours ago, CamGTP said:

Years ago I had a 2006 Sierra 2WD long bed 5.3 work truck and even with 255k miles on the clock it could return 23-24mpg on the freeway in the summer. It had a 35 gallon tank, so I could have gone like 750-800 miles lol.

Nice to see a newer truck get better mileage.

Our ‘05 Suburban 2wd got great MPG’s as well.

SouthwestORV · January 28, 2020

2 hours ago, Grumpy Bear said:

Kudo's on your results. Two questions. How fast did you drive ballpark? What wheels are those? NICE!

That’s the key! I never set the cruise higher than 60mph. Funny thing is...you don’t really get where you’re going much faster at 65mph, or even 70mph. I’ve noticed that mph and throttle input make a huge diff on these trucks!
These wheels were the cheapest rim offered by Discount Tire for this pickup, then I put a one size up from stock Cooper highway tire on there. I love how it turned out. Still very good road manners.

JB45 · January 28, 2020

So I've got a 2015 GMC Sierra 5.3 4x4, double cab, 6.5 bed stock wheels and tires no lift. When I first got the truck, went on a 5 hour interstate trip running 70-75. It was cold and rainy and I only got 14 mpg. Very disappointed since it's advertised for 22. Now after about a week of grandma driving I've graduated to 15.5 mainly highway. I've calculated it manually btw. What's the deal? I don't expect to get 20-22 but would be happy with 18. Here's my thoughts.

It's warmed up in the 40s where I live the last couple days.

Coming back from the 5hr trip I actually ran 80 so I spent less time in AFM mode. This was the time frame which I got 15.5

From the dealership it had a fresh 5w-30 oil change, seriously planning on going to 0w-20, like the manufacturer intended.

My rear tires are 30psi, so probably going to top them off tomorrow while changing my oil.

Is this enough to make me get that bad of fuel mileage? Thoughts, what are you guys doing to get even 18? And please try to keep it specific to the GenV 5.3 ecotec. If your throttle body 350 got 17 one time that's great but doesn't really relate. Lol.

Edited January 28, 2020 by JB45

Grumpy Bear · January 28, 2020

9 hours ago, JB45 said:

So I've got a 2015 GMC Sierra 5.3 4x4, double cab, 6.5 bed stock wheels and tires no lift. When I first got the truck, went on a 5 hour interstate trip running 70-75. It was cold and rainy and I only got 14 mpg. Very disappointed since it's advertised for 22. Now after about a week of grandma driving I've graduated to 15.5 mainly highway. I've calculated it manually btw. What's the deal? I don't expect to get 20-22 but would be happy with 18. Here's my thoughts.

It's warmed up in the 40s where I live the last couple days.

Coming back from the 5hr trip I actually ran 80 so I spent less time in AFM mode. This was the time frame which I got 15.5

From the dealership it had a fresh 5w-30 oil change, seriously planning on going to 0w-20, like the manufacturer intended.

My rear tires are 30psi, so probably going to top them off tomorrow while changing my oil.

Is this enough to make me get that bad of fuel mileage? Thoughts, what are you guys doing to get even 18? And please try to keep it specific to the GenV 5.3 ecotec. If your throttle body 350 got 17 one time that's great but doesn't really relate. Lol.

Your answer is:

10 hours ago, SouthwestORV said:

That’s the key! I never set the cruise higher than 60mph. Funny thing is...you don’t really get where you’re going much faster at 65mph, or even 70mph. I’ve noticed that mph and throttle input make a huge diff on these trucks!
These wheels were the cheapest rim offered by Discount Tire for this pickup, then I put a one size up from stock Cooper highway tire on there. I love how it turned out. Still very good road manners.

EPA test isn't done at 80 mph.

L86 All Terrain · January 28, 2020

Great mileage, well spec'd truck to be a hyper mile'r. Personally I cant drive that slow. I get about 16mpg with my 6.2L on a 500mi trip. I do the 250 mi (one way) drive in 3.5-3.75hrs at 67mph passing everyone I catch as soon as safely possible. If I drove the limit of 55 (averaging lower than 55 because of slow traffic) and didn't pass anyone it's easily a 4.5hr drive and I'd be lucky to get 19mpg with my tires, so the cost of time is more valuable than $10-15 in gas when I am on my own leisure time as I don't get much of it. Two-way traffic and one lane makes a huge difference in commute times. You wont notice it on your wonderful concrete multilane freeways of the USA. Stock tires my computer would tell me 23 was my best, but now 16mpg on a day to day in the summer, I can live with that for 420hp and 33's. Don't worry about saving $10 in gas and taking an extra half an hour when your boss is paying you $30 an hour, your losing money for your company.

JB45 · January 28, 2020

1 hour ago, Grumpy Bear said:

Your answer is:

EPA test isn't done at 80 mph.

Yes I understand that, but I actually got 1 mpg better the tank running 80 than 70, that's why I added that. I've read about guys with leveling kits and 33s getting 18, running 70. That's why it's suprising that even when driving easy(70 mph max interstate) I can't break 15.5 with a bone stock, AFM, no tune, etc. This is with multiple tanks, driving the same long interstate commute. I didn't notice much difference between 70 or 80 mph tanks. I'm not expecting 25 mpg, that takes patience and dedication. Just seeing if anyone else has this

JB45 · January 28, 2020

49 minutes ago, L86 All Terrain said:

Great mileage, well spec'd truck to be a hyper mile'r. Personally I cant drive that slow. I get about 16mpg with my 6.2L on a 500mi trip. I do the 250 mi (one way) drive in 3.5-3.75hrs at 67mph passing everyone I catch as soon as safely possible. If I drove the limit of 55 (averaging lower than 55 because of slow traffic) and didn't pass anyone it's easily a 4.5hr drive and I'd be lucky to get 19mpg with my tires, so the cost of time is more valuable than $10-15 in gas when I am on my own leisure time as I don't get much of it. Two-way traffic and one lane makes a huge difference in commute times. You wont notice it on your wonderful concrete multilane freeways of the USA. Stock tires my computer would tell me 23 was my best, but now 16mpg on a day to day in the summer, I can live with that for 420hp and 33's. Don't worry about saving $10 in gas and taking an extra half an hour when your boss is paying you $30 an hour, your losing money for your company.

Do you have the new 6.2 with the 10 speed? If so, how do you like it? I think that would be the next truck I would want.

truckguy82 · January 28, 2020

11 hours ago, JB45 said:

So I've got a 2015 GMC Sierra 5.3 4x4, double cab, 6.5 bed stock wheels and tires no lift. When I first got the truck, went on a 5 hour interstate trip running 70-75. It was cold and rainy and I only got 14 mpg. Very disappointed since it's advertised for 22. Now after about a week of grandma driving I've graduated to 15.5 mainly highway. I've calculated it manually btw. What's the deal? I don't expect to get 20-22 but would be happy with 18. Here's my thoughts.

It's warmed up in the 40s where I live the last couple days.

Coming back from the 5hr trip I actually ran 80 so I spent less time in AFM mode. This was the time frame which I got 15.5

From the dealership it had a fresh 5w-30 oil change, seriously planning on going to 0w-20, like the manufacturer intended.

My rear tires are 30psi, so probably going to top them off tomorrow while changing my oil.

Is this enough to make me get that bad of fuel mileage? Thoughts, what are you guys doing to get even 18? And please try to keep it specific to the GenV 5.3 ecotec. If your throttle body 350 got 17 one time that's great but doesn't really relate. Lol.

70mph I’m getting 24-25mpg all day in my 6.2.

When I set my record it was 27mpg, cruise set on 65mph exactly on a perfectly flat road.

JB45 · January 28, 2020

6 minutes ago, truckguy82 said:

70mph I’m getting 24-25mpg all day in my 6.2.

When I set my record it was 27mpg, cruise set on 65mph exactly on a perfectly flat road.

Plus awesome factory horsepower. No replacement for displacement. Yeah I want the 6.2 next, does yours have the 10 speed?

KARNUT · January 28, 2020

With my 14 GMC 22MPG was the rule at 72 MPH. Avoiding a traffic problem driving on a secondary road at 60 MPH for a decent amount of miles I got 24 MPG. That was with a tune and cylinder deactivation turned off.

JB45 · January 28, 2020

9 minutes ago, KARNUT said:

With my 14 GMC 22MPG was the rule at 72 MPH. Avoiding a traffic problem driving on a secondary road at 60 MPH for a decent amount of miles I got 24 MPG. That was with a tune and cylinder deactivation turned off.

That's awesome. That's what I was hoping for. At this point I see no reason to keep the AFM, it drives me nuts and it's obviously not helping my fuel economy. Plus I'd like to do an engine and TCM tune because I don't really like the way it shifts and feels like there is plenty of horsepower there when torque management and whatnot isn't in the way. Did you run 0w-20 oil? And did you notice a significant drop in mpgs during cold weather? I'm from Missouri so it's not like the Frozen North or anything but it's been in the 20-30s and that's when I was getting 14.

KARNUT · January 28, 2020

2 minutes ago, JB45 said:

That's awesome. That's what I was hoping for. At this point I see no reason to keep the AFM, it drives me nuts and it's obviously not helping my fuel economy. Plus I'd like to do an engine and TCM tune because I don't really like the way it shifts and feels like there is plenty of horsepower there when torque management and whatnot isn't in the way. Did you run 0w-20 oil? And did you notice a significant drop in mpgs during cold weather? I'm from Missouri so it's not like the Frozen North or anything but it's been in the 20-30s and that's when I was getting 14.

It was summertime, I didn’t see much difference in the winter. Mine was a 5.3, 342 gear, 20 inch factory wheels and 0-20 factory spec oil. I did lots of testing was cylinder deactivation on and off with no real change. I used hypertec hand held to turn off cylinder deactivation among other adjustments.