Fuel efficiency drop in newer models ?

[WalleyeMikeIII]

Many States require such labeling, but some do not. Patrick De Haan from GasBuddy tells us which ones don't:

Does your state require ethanol labeling? - GasBuddy

It's a fact that many know about ethanol- it contains less energy than conventional gasoline, and results in lower fuel efficiency. Some states have moved

www.gasbuddy.com

Spoiler: California, District of Columbia, Hawaii, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, New Jersey, New Mexico, North Carolina, and Ohio

Gas Buddy indeed says MN not required to label, but my experience here is opposite. Furthermore, the law requires 10% biofuel (as an oxygenate) in all gasoline sold at retail for on road use (All fuel sold in MN for on road use must be "Oxygenated Gasoline") and further restricts to an ethanol content of 9.2-10%.
Almost all stations label whether it contains Ethanol, and How much, and they definitely label if it does not contain ethanol ("Non Oxygenated" fuel here is, by law, only usable in vehicles not designed for it, off road vehicles, boats, and small engines, and must be minimum 91 octane.) It is not dyed, however, so not sure how exactly they can enforce it. This sometimes leaves one in a lurch to either choose to violate the 'Oxygenated Fuel' law or put lower octane than required in a vehicle, since often the ethanol free is the only 'premium' available at a station.

 

[Marky Dissod]

Forgetting to multiply the gearbox ratios by the axle(s) ratio always creates problems.
Also keep in mind that, from the 70s til the noughties,
axle ratios for vehicles under about 7000lb were artificially pressured by CAFE MpG scores to be lower than desired.

Speaking in terms of GMTs weighing 5000lb or more:
4L60E with anything under 3.73 wastes fuel AND sacrifices gearbox durability / longevity.
6L80E with anything under 3.42 wastes fuel AND sacrifices gearbox durability / longevity.

I do hope they really take advantage of what is possible with 10 speeds ...

NO, YOU DO NOT - at least, not the way automakers are going to take advantage.

*Prepare for turbo-3-inlines to replace 4-inlines, turbo-4-inlines to replace V6s, (V6s will be replaced by 6-inlines),
twin turbo-6-inlines to replace most light-duty / passenger V8s (Stellantis Hurricane turbo-6-inlines killed Hemi V8s),
larger twin turbo-V8s will be EXCLUSIVELY for 2500-&-up work trucks and commercial vehicles,
smaller twin-turbo V8s will compete with larger twin turbo 6-inlines for ne-plus-ultra-luxe-high-performance cars
(twin-turbo V8s are already pretty much done killing V10s & V12s)

Also, due to more 8- 9- & 10-speed transmissions and more turbos,
Variable Valve Timing will look more and more like the Atkinson Cycle, with torque peaking OVER 4200RpM.

 

[viven44]

4L60E with anything under 3.73 wastes fuel

Agreed on the longevity.. no doubts there. Are you talking about city or highway cruising mpg ? Why would a 3.42 not fare better on highway ? For city, I could agree…

And all that Turbo future is scary (from a service standpoint).. maybe I’m used to working on simple things. Glad I started collecting engines/transmissions from wrecked trucks and parts trucks to keep my “fleet” going.

 

[Marky Dissod]

6L80 8L90 & 10L80 prove that 4L60 was effectively wasting fuel in metro/urban stop'n'go ...
GM almost always used 4L60's axle gear to bias the tradeoff toward highway MpG, sacrificing city MpG.
If we use the axle to bias the tradeoff toward city MpG, we sacrifice some highway MpG.

8L90E x 3.23: ... 14.73 ... 9.60 .... 6.72 .... 5.46 . . . . . . . 4.10 ... 3.231 ... 2.75 . . . . . . . 2.10 (7.01 Spread)
4L60E x 3.42: . . . . . . . 10.47 . . . . . . . . . 5.58 . . . . . . . . . . . . 3.42 . . . . . . . . 2.39 (4.43 Spread)
4L60E x 4.10: . . . . . 12.55 . . . . . . . 6.68 . . . . . . . . . . . 4.10 . . . . . . . . 2.86 (4.43 Spread)

Hopefully turbos get better thermal maintenance / longevity - otherwise turbos will NEVER last as long as their engines ...
especially if 4s & 6s start screwing with Cylinder Confusion ...

 

[Big Mama]

You number guys are awesome but way over my head. I just got a 23 Sierra Denali with the 10 speed. Longevity remains to be seen since they’re relatively new. From a seat of the pants perspective I can say the 10 speed it much more responsive than my 07 Yukon Denali. I find myself wanting to hit the gas more often due to this.
I wonder if that has anything to do with real world mpg vs calculated EPA numbers.
The mpg in the Sierra is almost 50% higher than the Yukon.

 

[viven44]

The low-end response I must admit is quite good on the 2024... I haven't driven it much yet since we bought it, but that was my recollection the day of purchase.

Wife is a very conservative drive. Per wife just now...

Our 2024 4x4 with the 3.23 axle gets 15mpg city / 19-20mpg highway... hoping this improves after the break-in period based on previous comments on this thread.

Our 2018 with the 3.42 axle (Tow pkg) 4x2 was used mostly on highway.... we got ~14 mpg city but highway is where it really did wonderful >=26mpg highway. Wife consistently challenged herself to get better highway mpg, and claims to have got even 29mpg during one trip... To be fair we never double checked the mpg indicator with manual calculations. And I must say the 2018 impressed us so much that we stuck with the GM brand for the next purchase. (We lost the AC condenser .. the usual leak on the weld... but I was able to replace that easily... R1234yf was the most expensive part of all that....)

The 2002 Yukon 4x2 I got recently with the 3.42 axle got about 13 mpg city at the most recent fill up.. I keep a close eye on the gas guzzlers I drive no idea on highway as I haven't had to drive much highway.

 

[viven44]

Towed 8200# yesterday with empty trailer weighing 2200#

Averaged 16.5mpg with empty trailer and 12.4mpg with load .. drove conservatively in tow mode 55mph and no higher than 60mph as it started fishtailing

 

[Marky Dissod]

Towed 8200# yesterday with empty trailer weighing 2200lb
Averaged 16.5mpg with empty trailer and 12.4mpg with load ... drove conservatively in tow mode 55mph and no higher than 60mph as it started fishtailing

I'm almost sure that more axle gear would neither improve the 12.4MpG-towing, nor the 16.5MpG-unladen ... the only thing GM can possibly do to the 10speed is improve the ratios relative to each other; 10 speeds seems like more than enough.

Are you talking about city or highway cruising MpG? Why would 3.42 not fare better on highway? For city, I could agree ...

Unladen, with 3.42, it depend on how fast you prefer to cruise on the highway, because at a certain point, 4th gear can't put enough power through the tires to maintain speed against drag.
Laden / city, it should be obvious that 4.10 gives the 4L60E a chance to spend more time in 3rd or 4th,
and less time in 2nd.

 

[strutaeng]

Towed 8200# yesterday with empty trailer weighing 2200#

Averaged 16.5mpg with empty trailer and 12.4mpg with load .. drove conservatively in tow mode 55mph and no higher than 60mph as it started fishtailing

View attachment 442144

Nice. What's the story with the Ford truck? Is that an F250?

 

[vcode]

Towed 8200# yesterday with empty trailer weighing 2200#

Averaged 16.5mpg with empty trailer and 12.4mpg with load .. drove conservatively in tow mode 55mph and no higher than 60mph as it started fishtailing

View attachment 442144

Good thing I don't live in Texas. I'd have a yard full of vehicles!