6.2, power on tap plus respectable MPG

Grjfer · December 29, 2018

1800+ mile trip in the 2018 GMC Sierra 1500 SLT 4x4 6.2. Two adults, 2 boxers and between 500-600# of cargo. Truck is totally stock except for the Falken Wildpeak at3w 275 60r20 XL tires, undercover bed cover. 875 mile on it at time of departure. This is my return trip milage. Initial trip milage was 21.4.

Grjfer · December 29, 2018

Initial trip milage.

JimCost2014 · December 29, 2018

2 minutes ago, Grjfer said:

Initial trip milage.

Very nice, if you stay out of the "fun pedal" these numbers are achievable. Have been averaging almost 23 mpg going to the beach and back (400 - 800 mile round trip).

71_340 · December 29, 2018

Did you hand calculate? My truck's MPG readout is off by almost 2 mpg and my hand calculated average is usually in the 19 to 20 range driving "normal" which isn't bad for a big heavy truck with a 6.2L engine.

Mileguru · December 29, 2018

27 minutes ago, 71_340 said:

Did you hand calculate? My truck's MPG readout is off by almost 2 mpg and my hand calculated average is usually in the 19 to 20 range driving "normal" which isn't bad for a big heavy truck with a 6.2L engine.

True. My DIC always reads 10-20% too high.

1SLOW1500 · December 29, 2018

Why so low? What trans? Is it lifted or leveled, tire size changed?

I get 20mpg at 570hp in a 5.3l a6 with 24" 33tall and 12 wide tire. Lowered crew cab with 2 batteries,turbo kit, sound system.

Not trying to bash you just saying I thought the 6.2 a8 gets higher?

midwestdenaliguy · December 29, 2018

3 hours ago, 1SLOW1500 said:

Why so low? What trans? Is it lifted or leveled, tire size changed?

I get 20mpg at 570hp in a 5.3l a6 with 24" 33tall and 12 wide tire. Lowered crew cab with 2 batteries,turbo kit, sound system.

Not trying to bash you just saying I thought the 6.2 a8 gets higher?

Can't answer for the OP but what I can tell you is that I got 21.5 mpg on my last long trip with my 6.2 (8 speed) and I have a lift, 10 ply 33's, and various accessories mounted. Also had luggage and some other items in the cab and bed.

When I didn't have a lead foot (rare) the best I did was 24.1 mpg, but that was before all my mods. I'll never see that again, plus I don't want to pay that much attention to my mpg's. I'd rather enjoy the road and my music than constantly monitor my dash and watch the pedal.

1SLOW1500 · December 29, 2018

Can't answer for the OP but what I can tell you is that I got 21.5 mpg on my last long trip with my 6.2 (8 speed) and I have a lift, 10 ply 33's, and various accessories mounted. Also had luggage and some other items in the cab and bed.

When I didn't have a lead foot (rare) the best I did was 24.1 mpg, but that was before all my mods. I'll never see that again, plus I don't want to pay that much attention to my mpg's. I'd rather enjoy the road and my music than constantly monitor my dash and watch the pedal.

Yeah 24 is what I thought the 6.2 a8 was known for. I don't care about mpg but was suprized I got so good with all I have in my truck then to hear some stock trucks getting worst is interesting.
Leaving the spot I did some test hits at my mpg just kept climbing. Short ride back home but still very good.

Sent from my SM-N960U using Tapatalk

Grjfer · December 29, 2018

9 hours ago, 1SLOW1500 said:

Why so low? What trans? Is it lifted or leveled, tire size changed?

I get 20mpg at 570hp in a 5.3l a6 with 24" 33tall and 12 wide tire. Lowered crew cab with 2 batteries,turbo kit, sound system.

Not trying to bash you just saying I thought the 6.2 a8 gets higher?

Read the first post. All questions answered except trans(8 speed).

I'm not comparing my mileage to yours, I'm just stating that the 6.2L with the 8 speed is a great all around drive train. Capable of good mileage and fun to drive.

Grjfer · December 29, 2018

32 minutes ago, 1SLOW1500 said:

Yeah 24 is what I thought the 6.2 a8 was known for. I don't care about mpg but was suprized I got so good with all I have in my truck then to hear some stock trucks getting worst is interesting.
Leaving the spot I did some test hits at my mpg just kept climbing. Short ride back home but still very good.

Sent from my SM-N960U using Tapatalk

Last 50 miles don't mean a hill of beans. I can milk some very good 25 & 50 mile numbers by picking my route and a judicious amount of coasting.

Let see some 400 mile #s.

Imcrazy · December 29, 2018

You guys are getting some killer MPG, is the terrain you're driving pretty flat? What is your average speed over these trips? I find that if I can keep my 5.3 / 6speed 2016 Double Cab around 55-60mph I can get these kind of numbers on pretty flat terrain but, if I have to go up to 'highway speed' of 65-75mph I am lucky to get 18-20 mpg depending on if I am running winter or summer gas...

My truck is stock except I removed the lower front valance & I have 275/65/18 Cooper AT tires instead of the stock Goodyear highway tires..

1SLOW1500 · December 29, 2018

I never drive the truck that much it is just one of my around town cars. I but 5k miles on in 2 years.

Also I see in picture you have afm/DOD. I disable mine V8 only. So your truck is stock? What gears? I may have to take a 6.2 a8 truck out for a weekend trip and see.

midwestdenaliguy · December 29, 2018

My set up is a 2016 Denali, 6.2, 8 speed, 3.23 gears, 2.5" front and 1" rear lift, AFM deactivated with a DiabLew tune, 33" 10 ply AT tires, Borla ATAK catback exhaust, with various accessories mounted like an LED light bar behind my grille, a bed cover, and the rear seat storage box that's full with ratchet straps, roadside emergency kit, tow hitch, gloves, etc.

My daily average is 18 mpg and I do about 20k miles per year. That's a mix of city and highway driving with a lead foot. On my long trips (2-3 per year of driving from St Louis to see family in Michigan) I can break 21 mpg if I go about 70-75. My normal highway speed of 80-85 I get around 19 mpg. There are so many factors that go into mpg's though that it's not all apples to apples. My truck is modded and tuned (500hp) and I like speed/power over mpg's. I believe you could easily mod your truck to get 25+ mpg, but that also depends on where you live.

duckcommander · December 29, 2018

400 mile trip home on my new 18 cc4x4 stock 6.2 8sp 25.9 mpg

Jimmyc! · December 29, 2018

13 hours ago, 71_340 said:

Did you hand calculate? My truck's MPG readout is off by almost 2 mpg and my hand calculated average is usually in the 19 to 20 range driving "normal" which isn't bad for a big heavy truck with a 6.2L engine.

I always hear about how the Driver Information Center (DIC - yes I had to look that up) is 10-15% off hand calculated. I have not found that on my 2015 Silverado 5.3 - Totalled, 2015 Sierra 6.2 - Traded, or my 2018 Sierra 6.2. I'm finding less that a 5% margin of error. I can't be the only one seeing this am I?

Edited December 29, 2018 by Jimmyc!