Fuel efficiency drop in newer models ?

[vcode]

Yeah if it was an XL, maybe would add a few hundred pounds... not enough to matter. You will see the rated fuel economy doesn't vary greatly

More power -- yes but simply shifting the torque to the higher RPM bands. HP is nothing but Torque x RPM / 5,252... yeah torque has gone up too (325 vs 383), but again peak in the upper RPMs.

What matters is fuel economy and tow rating for a truck. On the 1/2 tons, are you going to say GM has done a spectacular job in the last 20 years on those 2 metrics ?

Curb weight is up 800-1000 lbs on the 2024 from what I can tell. Are axle ratios the same? Final drive ratio is 0.7 for the 2002 4 speed vs 0.63 for the 10 speed. Not much difference there. A friend had a 2004 Tahoe and he was lucky to get 18 mpg on the highway. I often see 20 mpg for folks with later models here. Only so much you can do pushing a barn thru the wind.....

 

[jfoj]

Fuel economy on these bricks starts to rapidly diminish over 65 MPH. The problem is when people are pushing these bricks at 75-80 MPH, you cannot expect much, this is not how the EPA fuel economy is tested.

Additionally anyone that has a 6.2l is likely using the right pedal a lot to get around slower traffic, just bring up the Fuel Economy display and keep it on the dash, watch what the center portion is showing, you will see what happens on inclines or when the right pedal is used. If the vertical bar drops to around 25% on the fuel economy, you are likely into 80%+ engine loading.

Here a shot of a recent trip I took and I was not trying to be thrifty, I had to meet a deadline. I have done better, but it depends on a lot of factors.

 

[viven44]

Your 2024 has way more features and way more safety.

You act like none of that matters. Or how much larger the interior is?

I mean if you just wanna believe yourself that's fine but objectively on this you are incorrect respectfully.

Do you really believe all those feature are going to last 20 years ?

Do the terms "galvanic corrosion, solder joint fatigue cracking, kirkendall voiding, electromigration, dielectric breakdown" mean much ?

Unfortunately, that's all I can think about when I look at all the computer modules in modern vehicles. I work in reliability engineering of consumer and automotive grade semiconductor chips. Since about 2009 (housing and job recession), the quality paradigm has gone from "no compromises" to "good enough"... Good enough in automotive chips is 10 year lifespan. That is all the AEC (Automotive Electronics Components) expectation is.

The only good thing about new stuff is that if they breakdown quickly, there will be need for more, and will create more jobs .. need to feed more mouths as time goes on in the world so I'm happy to play the game to a certain extent, and Yeah I whole heartedly agree that safety features are a must, that is why my family members are in a 2024 Suburban... I didn't force down even a full time use of the 2002 Yukon on them... I let them decide what is best for them.. just requested them to avoid using the 2024 for short trips. For my personal use I am disillusioned with poor quality everywhere and the high level of focus of Wall street on 'profits'.. and don't care anymore.

PS: Example of where my personal requirements are.. My "forever AC" had to be on full blast today as it was about 90 degrees outside in TX. haha

 

[Blackcar]

Some of these post that posters are quoting known problem and quality I don't know why they even looked at vehicle they purchased.

 

[vcode]

Anyway.... I think we've moved onto Turbo here.... but thats not the point of this thread.

I'll put it another way...

Spot the problem

Our 2002 Yukon and our 2024 suburban have the same engine displacement (5.3L)
Our 2002 is just a simple port injected engine and our 2024 has cylinder deactivation and DI fuel system
Our 2002 has a 4-speed transmission and our 2024 has a 10 speed
Our 2002 is more fuel efficient than our 2024 for city/hwy driving
Our 2002 can tow as much as our 2024

I hope it is clear

Wait, is your 2024 a 4X4? You can't compare that to a 2WD 2002 model.....

 

[Scarey]

I don’t see a data port on that wing window. How do you do the software updates?

 

[viven44]

Wait, is your 2024 a 4X4? You can't compare that to a 2WD 2002 model.....

Well so be it. The 2024s are rated for the same city mph 4x4 or otherwise. Highway is 10% better on paper on 4x2s.

Anyway, just disappointed that the engineering decisions weren’t the best and not much has changed in 20 years. We discussed this in the other thread but the 6.6L without any DFM gimmicks is rated for the same fuel economy on the 2500 trucks….

 

[DuraYuk]

Do you really believe all those feature are going to last 20 years ?

Do the terms "galvanic corrosion, solder joint fatigue cracking, kirkendall voiding, electromigration, dielectric breakdown" mean much ?

Unfortunately, that's all I can think about when I look at all the computer modules in modern vehicles. I work in reliability engineering of consumer and automotive grade semiconductor chips. Since about 2009 (housing and job recession), the quality paradigm has gone from "no compromises" to "good enough"... Good enough in automotive chips is 10 year lifespan. That is all the AEC (Automotive Electronics Components) expectation is.

The only good thing about new stuff is that if they breakdown quickly, there will be need for more, and will create more jobs .. need to feed more mouths as time goes on in the world so I'm happy to play the game to a certain extent, and Yeah I whole heartedly agree that safety features are a must, that is why my family members are in a 2024 Suburban... I didn't force down even a full time use of the 2002 Yukon on them... I let them decide what is best for them.. just requested them to avoid using the 2024 for short trips. For my personal use I am disillusioned with poor quality everywhere and the high level of focus of Wall street on 'profits'.. and don't care anymore.

PS: Example of where my personal requirements are.. My "forever AC" had to be on full blast today as it was about 90 degrees outside in TX. haha

View attachment 457258

I've replaced modules on cars old and new. That's nothing new and nothing to be concerned about.

 

[viven44]

I've replaced modules on cars old and new. That's nothing new and nothing to be concerned about.

You are partly correct. You are only addressing the “can it be done” part. We have since about 2017-18 or so moved onto the “Apple” model of doing modules. The OEMs are highly customizing the analog and digital functions of these modules to where aftermarket modules simply won’t exist or would be cost prohibitive due to licensure cost. That means you will need to buy the modules directly from the OE like Ford or GM moving forward. No more Dorman or Cardone module.

Anyway.. see where I’m going ? These vehicles are going to be money pits, assuming they can even be fixed. For example, I simply don’t have the appetite to spend $2K on a video processing module so I can continue to run my cameras.

And its not that I’m not familiar with module programming and stuff. I’ve been there done that and choosing to play by my set of rules that’s all.

 

[DuraYuk]

You are partly correct. You are only addressing the “can it be done” part. We have since about 2017-18 or so moved onto the “Apple” model of doing modules. The OEMs are highly customizing the analog and digital functions of these modules to where aftermarket modules simply won’t exist or would be cost prohibitive due to licensure cost. That means you will need to buy the modules directly from the OE like Ford or GM moving forward. No more Dorman or Cardone module.

Anyway.. see where I’m going ? These vehicles are going to be money pits, assuming they can even be fixed. For example, I simply don’t have the appetite to spend $2K on a video processing module so I can continue to run my cameras.

And its not that I’m not familiar with module programming and stuff. I’ve been there done that and choosing to play by my set of rules that’s all.

That's been the case longer than you think. And most electronics need to be coded anyways. Idk that I've ever used dorman for any module lol.

 

[viven44]

That's been the case longer than you think. And most electronics need to be coded anyways. Idk that I've ever used dorman for any module lol.

If you can code a 2024 GM module more power to you. Most people need to go to the dealership.

Look at this one guy. His Yukon has a seemingly mundane problem P0304... apparently a GMC corp specialist has been summoned now.... complexity is at a point where even dealers won't be able to fix these things... bottom of my heart I hope I'm wrong about all of this because it would suck if all these vehicles are simply scrapped as cost of repairs would exceed their value quickly.

Cylinder 4 miss-fire P0304

Bought a 2025 yukon denali and have had it in shop multiple times. First intake manifold gasket then a lifter failure. Am telling them to replace coil and plug because they can't seem to fix the cylinder 4 from missfiring. What else would cause this? Computer, loose wire?

www.tahoeyukonforum.com

Topology map on our 2024. I see many things that make my head spin.

 

[DuraYuk]

If you can code a 2024 GM module more power to you. Most people need to go to the dealership.

Look at this one guy. His Yukon has a seemingly mundane problem P0304... apparently a GMC corp specialist has been summoned now.... complexity is at a point where even dealers won't be able to fix these things... bottom of my heart I hope I'm wrong about all of this because it would suck if all these vehicles are simply scrapped as cost of repairs would exceed their value quickly.

Cylinder 4 miss-fire P0304

Bought a 2025 yukon denali and have had it in shop multiple times. First intake manifold gasket then a lifter failure. Am telling them to replace coil and plug because they can't seem to fix the cylinder 4 from missfiring. What else would cause this? Computer, loose wire?

www.tahoeyukonforum.com

Topology map on our 2024. I see many things that make my head spin.
View attachment 457275

Gm has had a mdi box for a long time now. The days of the tech 2 have been over. And there are aftermarket solutions to help the DiY person. With that said idk why you think a dealer won't be able to fix these. Honestly modern diagnostics have come a long way and I love a good modern wiring diagram on a computer over a black and white printed one buried in a stained book.

I love the modern stuff. Its not scary at all.

 

[viven44]

Hey this guy thinks alike.. he drives an early 2000s buick lol

He also talks about the 'conspiracy'... Companies care about making money. They do care about reputation, but they also know people have no better choice these days. Ford / GM / Stellantis are all under the same pressure to cut costs. There is significant competition and everyone has to use all means necessary to cut costs (off shore manufacturing being one of the tricks in this day and age).

 

[rlhmarines]

Fuel economy on these bricks starts to rapidly diminish over 65 MPH. The problem is when people are pushing these bricks at 75-80 MPH, you cannot expect much, this is not how the EPA fuel economy is tested.

Additionally anyone that has a 6.2l is likely using the right pedal a lot to get around slower traffic, just bring up the Fuel Economy display and keep it on the dash, watch what the center portion is showing, you will see what happens on inclines or when the right pedal is used. If the vertical bar drops to around 25% on the fuel economy, you are likely into 80%+ engine loading.

Here a shot of a recent trip I took and I was not trying to be thrifty, I had to meet a deadline. I have done better, but it depends on a lot of factors.

View attachment 457257

I like to keep a similar screen up in the new Tahoe but it doesn’t have the average speed displayed like in yours anymore. I will continue playing around with the display options but I don’t believe it’s available anymore in the refreshed SUV’s.

I told my wife when she was driving on a leg of our trip to keep it below 82 mph to see what kind of mpg we could get on our 6 hr drive. I also believe people are just driving faster without fully knowing the consequences to their fuel economy especially above a certain rpm or mph in these much taller versions that we’re driving now. Our ‘25 Tahoe towers over my ‘01 Tahoe especially the hood area, I almost need a step ladder to reach the dip stick so as to not touch the fender on the new one.

Rpm and how smooth you apply the gas and brakes makes a huge impact on your mileage plus if you live in mountainous terrain or have a good amount of rolling hills you can expect lower than normal fuel economy but your driving style is the biggest factor in my opinion from decades of driving experience.

 

[jfoj]

The Fuel Economy Display is very helpful if and when you start to pay attention and learn how it functions.

You can easily see when you are coasting, on light throttle, pulling grades and so forth and how it impacts your fuel economy.

While not a 100% correlation, I have figured out when the center bar graph drops to around 25% or lower, if the transmission has not downshifted to the point the engine RPM is over 2000 RPM, this is where you start loading the hell out of the engine and using all the Torque. At or below the 25% indication is where you start loading the engine to 80-100% if the engine RPM is under 2000 RPM!!!! Watch this bar graph carefully next time you take a trip and you will soon start to understand where your fuel is going.

 

[Scarey]

I’m wondering if there are any ill effects of driving in tow mode. You give up gas economy but in are in the tourque rang more solidly. You obviously are giving up mpg but it just feels it in a bette spot, quicker response to power. Not lugging as much. Any thoughts?

 

[jfoj]

I have not played with the Tow Mode much yet. As a side not, it has been confirmed that even in Sport and Tow mode, DFM is still active, maybe not as active, but still active.

Typically Tow mode will delay upshifts and may even keep the transmission from shifting into 10th gear?? I also assume Tow Mode may downshift earlier, but again, this is an assumption at this point in time. I do believe Tow Mode also opens the Active Grille Shutters, I played with it on one drive for a short while looking at the the engine and oil temps and I believe the Active Grille Shutters are open, but I would need to put a camera in to watch the shutters or see if I can monitor the shutter behavior with a scan tool. I expect the TCM changes and opening the Active Grille Shutters will impact fuel Economy in a negative way, but by how much, I have no idea.

I may try to pull some data to monitor Tow Mode, but I just have a lot on my schedule at the moment.

 

[viven44]

Wanted to provide some towing mpg feedback for the usual loads I tow.... I purchased a new super duty last week (insurance restrictions on my classic trucks for towing). A new F350 w/ 7.3 Godzilla Gas, 4.3 rear axle, 10-speed. It is an XLT trim so has more electronic things that can break than I'd like but Ford won't let you get the 7.3 engine on a base XL :/

I would like to state that our 2024 Suburban does the job (towing ~7500lb) as good as the new super duty in the power/ease department.

Truck
Truck only ~ 14mpg driving 70mph
Truck with empty trailer 2300 lbs ~ 13.5 - 14mpg driving ~55-60mph
Truck with load on Trailer total 7500 lbs - 10.5mpg driving 55~60mpg

Suburban
Suburban only ~18.5mpg driving 70mph
Suburban with empty trailer 2300 lbs ~ 15.6 - 16mpg driving ~55-60mph
Suburban with load on Trailer total 7500 lbs - 12.5mpg driving 55~60mph

My only grievance with the Suburban is that the load has to be quite a ways back else the suspension is really weighed down, and with worries of exceeding tongue capacity as well. This was the main driver for a new truck.

A 2500 Suburban would be killer !

PS: I did seriously consider a 2500/3500 truck as well, very close, but we needed something with port injection that we could use for short trips (as we sold our 2002 Yukon) thus ended up with the F350.

 

[RST Dana]

Wanted to provide some towing mpg feedback for the usual loads I tow.... I purchased a new super duty last week (insurance restrictions on my classic trucks for towing). A new F350 w/ 7.3 Godzilla Gas, 4.3 rear axle, 10-speed. It is an XLT trim so has more electronic things that can break than I'd like but Ford won't let you get the 7.3 engine on a base XL :/

I would like to state that our 2024 Suburban does the job (towing ~7500lb) as good as the new super duty in the power/ease department.

Truck
Truck only ~ 14mpg driving 70mph
Truck with empty trailer 2300 lbs ~ 13.5 - 14mpg driving ~55-60mph
Truck with load on Trailer total 7500 lbs - 10.5mpg driving 55~60mpg

Suburban
Suburban only ~18.5mpg driving 70mph
Suburban with empty trailer 2300 lbs ~ 15.6 - 16mpg driving ~55-60mph
Suburban with load on Trailer total 7500 lbs - 12.5mpg driving 55~60mph

My only grievance with the Suburban is that the load has to be quite a ways back else the suspension is really weighed down, and with worries of exceeding tongue capacity as well. This was the main driver for a new truck.

A 2500 Suburban would be killer !

PS: I did seriously consider a 2500/3500 truck as well, very close, but we needed something with port injection that we could use for short trips (as we sold our 2002 Yukon) thus ended up with the F350.

Is your data based on vehicle calculations, or did you manually keep a log with real calculations?
I have logged all fuel consumption for the last 7 or so years. Many times the calculations differ from vehicle data. Many times better than reported, but occasionally, less than. Most less than comparisons were more city than highway driving.

 

[Big Mama]

I’m just starting to do this. I just got a new Sierra 2500 with a gas 6.6. It lets me track mpg alone or with my Rv or utility trailer. It’s difficult to do the small trailer bc I don’t use it much and don’t fill up after using it. Got any tips?