Do The 6 Speed Gas Really Get Better Mpg Then The 4

[topdj]

what kind of rpms do the 6 speed run on the highway vs the 4 and

[Stevens03]

what kind of rpms do the 6 speed run on the highway vs the 4 and

 

My 6.2 6-speed with 3.73 gears gets the same mileage as my previous 6.0 Vmax 4-speed with 4.10 gears. But it does turn a few less RPM's on the highway so I'm sure that helps offset the larger motor some.

 

I'm sure apples to apples, You'd pick up 1-3 mpg better.

[topdj]

well Im thinking of getting a 2500 since I have a plow, I don't really want to kill my 1500, I have to be mindful of plow operation right now, and I tow a 6200lb trailer in the summer with a big block boat. This would be much easier on a 2500 6.0 or even a duramax $$.

just wondered what the 6.0 with the 6spd and a tune could get on the highway. If its near my 1500 with a 4spd and 3.73 I turn 2000rpm on the highway

[Stevens03]

I'd say highway you'd get easily 18mpg with the 6.0 6-speed and 3.73 gears. My previous Vmax got 13-19mpg average with the 4-speed and 4.10's. Given the extra weight and all, plus the 6-speed, you'd most likely be about the same for an average.

[dewfpo]

The 6 speeds are supposed to get better mileage in city driving and mixed as well because the ECM has 6 gears to choose from and the engine isn't winding out as much.

 

DEWFPO

[sonjaab]

My 07 gmt-900 2500 4x4 6.0 6 speed 3:73s the best hiway mpgs are 16 mpg.

Around town.............10

My buds 07 gmt-900 4x4 1/2 ton 4 speed 5.3 3:73s gets 20+

 

Both bone stock!

[wanna_try_gmc]

I tend to be a little liberal with the speed limit here in MD, averaging 70-75 mph on a 45 mile hwy commute and I average about 15 in the summer and 14 now that it's winter......I have a 6.0 6 speed with 3.73's....I imagine I would increase my MPG's if I left a little earlier and slowed down but........

 

Dave

[music]

GM states that the 6-spd adds "up to 4% increase in efficiency" over the 4-spd auto. If you take AFM into account, it's probably closer to "none" in daily driving. Actual EPA city/hwy mpg rating on the 5.3/4-spd is 15/20. Same rating for the 5.3/6-spd is 15/21. I'd guess the non-AFM 6.0HD motor would benefit to the full "4%" improvement.

[jtramsey]

How come no one is getting better than 19 with the 6 spd?And with the AFM I would think someone would be getting better.

[Stevens03]

How come no one is getting better than 19 with the 6 spd?And with the AFM I would think someone would be getting better.

 

Heavy foot And some people are getting better than 19 mpg.

[mudfuel08]

With 295/70R17 Toyo Mt's. I'm turning about 1550 at 60mph and getting around 16mpg. I also have the Bully Dog GT installed.

[r6realtor]

Right now im getting 14.9-15mpg in the city only driving, with my 2011 2500, I have yet to get on the highway for more than a mile or two. When im doing about 70mph on that short stretch i think im at 1450-1500rpm?? but will double check.

[pm26]

My buds 07 gmt-900 4x4 1/2 ton 4 speed 5.3 3:73s gets 20+

 

I seriously doubt that. And even if, this would be in a very narrow speed range, with the AFM activated, and A/C off, crusing around 65 MPH. The moment you go over 70 MPH with A/C on, the highway mileage drops to 18 at best.

[music]

I seriously doubt that. And even if, this would be in a very narrow speed range, with the AFM activated, and A/C off, crusing around 65 MPH. The moment you go over 70 MPH with A/C on, the highway mileage drops to 18 at best.

 

Not true. I've measured mine by hand and checked the DIC many times. I've yet to average less than ~19.5 on long trips running the speed limit +5 (2wd mode). Usually, that's 65 to 75 mph. The DIC has registered over 20 on most trips, but actual is usually a few tenths less. FWIW, mine goes to 4-cyl mode a lot, where some folks on here report that it doesn't. I'm currently "stock". Also, ambient temps effect mpg. I notice a drop on very cold days with the same gas.

 

If I could get the same (or similar) mpg as my 5.3... it would be my next truck. That would mean that I could pull the camper more comfortably with minimal impact on daily driving. I don't see it being close, based on all input I've gotten (both online and from friends).

[sonjaab]

My 07 gmt-900 2500 4x4 6.0 3:73 turns about 2600 rpms at 65 mph.