The impossible: 04 Yukon XL Denali AWD

[mcrews]

get a gauge. you haqve to be 'top of mind' aware.

I am willing to bet you this:
1. you don't get there averaging 80 mph over 8 hours.
2. with a gauge, you'll find your average speed, while driving '80 mph' is probably 70mph.
3. But if you drive 70mph, your average will be closer to 64-65mph.

the reason is, unless you are on a flat raod all by yourself w/ no hwypatrol, you are slowing down for various reasons.
I drive 11-13hrs over 3 days on trips to texas and has records and personal exp to back this up.

also, mpg falls off exponetially above 65. So at 80mph you are pouring money down the drain compqred to 65.

but get a scangauge. I have had one for 3 yrs and swear by it.

since it is a hwy cruiser majority of the time, look at going up one size in tire size. there are plenty of threads on that topic...for cars. There seems to be some disagreement on trucks.

Concider changing out the rear gear. if in fact your on the freeway that much, it might be worth it.

pump up the tires. (see other threads)

[Cy-Gor]

My trucks computer will show instant MPG, though i am not sure how accurate it is. I assume this would be the same as the scangauge?

I dont really feel save driving as slow as 65 up and down I-35. the speed limit is now 70-75 all the time. and in dallas if you are driving under 75 it gets dangerous.

I didnt notice a huge difference from 65-80 as i originally thought. safety and time make me not want to slow down just to save a little bit of fuel.

[mcrews]

I dont really feel save driving as slow as 65 up and down I-35. the speed limit is now 70-75 all the time. and in dallas if you are driving under 75 it gets dangerous.

please.....spare me.
I've driven Austin to lewisville 3 times in the last 2 months. And I never went 75. But never dropped below 63 either.
You driving a friggin tank.......what are you playing videos and texting??????
why dont you 'feel safe'????

I was born and raised in Dallas also.

I also have an mpg screen on my Q45.
I just find the scangauge to provide other information that helps me focus on mpg oriented driving.

You need to get over some of your preconcieved notions.
the number one mileage improvemnet is : ADJUSTING THE NUT BEHIND THE WHEEL.

[mcrews]

you need to get on a real flat 5 mile strtch of road and run at 60, 65, 70, 75, 80.
Reset the mpg gauge on each run.
That will give u a reality ck on your mpg at each speed.

On ecomodder, we test our results. (see aba testing)
having factual data will help you decide if you want to change your behavior.
offhanded comments are excuses not facts or reason.
There is no "200 mpg carborator" to solve your problem.
You have to decide if each behavior change is worth it to you.
And the first one is slowing down AND understanding the facts (savings) are worth it.

[rmay635703]

Originally Posted by Cy-Gor

My trucks computer will show instant MPG, though i am not sure how accurate it is. I assume this would be the same as the scangauge?

I dont really feel save driving as slow as 65 up and down I-35. the speed limit is now 70-75 all the time. and in dallas if you are driving under 75 it gets dangerous.

I didnt notice a huge difference from 65-80 as i originally thought. safety and time make me not want to slow down just to save a little bit of fuel.

1. Scanguage can show you things your instant MPG won't and also it does not always match exactly. It allows you to alter how you accelerate, coast and drive and to know how slight differences in your gas pedal position dramatically change your fuel economy.

2. Historically I can't claim I had ever heard anyone mention increased safety and high speeds or speeding as an excuse or justification until about 8 years ago. I find it odd that absolutely no one mentioned increased safety with increased speeds years ago but now I see that one mentioned everywhere, not sure what changed. I doubt safety did on this regard.

3. You need to learn to control your throttling accurately allowing your vehicle to bleed and gain speed using hypermiling techniques. The degree to which you do this and avoid excessive acceleration & coast to stops will determine gains you get.
Just reducing speed will not improve your fuel economy if you also are stomping and braking more. On my Dodge going from 65mph to 80mph steady means going from 16mpg to about 11mpg,
I don't think that is INSIGNIFICANT and I doubt your Suburban is all that much different if you can keep the throttle rock solid steady.

On an aside my Suburban (not much different than yours just OLD) gets low 20's with a fuel leak. Before the fuel leak 23-26mpg was not unusual.
But then again mine is a diesel and 2wd.

Also what is a small amount of fuel? If you get (example) 18mpg @ 65mph and get 15mpg @ 80mph and you stated it would take 8 hours to get there at 55mph.

8x55 = 440miles per day

That is over 3 gallons of fuel saved per day or about $4380 saved per year.
Going from 15mph to 18mpg at least.

[Cy-Gor]

The 8 hour comment was directed at someone suggesting i go 45. which is how long it would probably take going from austin to witchita falls if i was driving that slow.

I get about 18mpg running 80ish, i dont know what my average speed on the trip is.

As far as safety is concerned, its more about traffic speed.
Between austin and dallas i could slow down and not really be a big deal. driving through dallas on 35 or the major highways going slower than 70 is kinda crazy at times. everyone drives 75 or faster. going 85 i get passed regularly.


Lastly, i am on cruise control for most of the trip which is why i was looking for physical mods and not techniques.

[ksa8907]

With that 6.0 ls engine im sure you can find some aftermarket engine parts that will increase efficiency and power.

[mcrews]

again, not buying the '70 is tooooo slow and dangerous'.

I'm all over arlington, south grand prarie, dallas, plano oak cliff.......
Trqaffic is NOT moving at (as a block) at over 70.

I WILL tell you (see my post...I CONFESS>>) that with the rolling hills on 35 I cant get the same mpg as I was getting in Sacramento.
All the more reason to drop 10mph.

What I find interesting is your tendencies to qoute 'extremes'
for example: you make a point to say you wont drive 45mph. That fine, but what about all the other reasonable suggestions that have beren made?
And claiming you HAVE to drive 80 to be safe....another extreme statement.

Have you aired up your tires?

[mcrews]

Originally Posted by ksa8907

With that 6.0 ls engine im sure you can find some aftermarket engine parts that will increase efficiency and power.

there is a newish thread on a 2005 caddy CTS-v that is getting 27+. he has done some engine mods. check his thread.

[MTrenk]

Lol, mcrews, you're awfully nasty sometimes.
As far as the physical improvements Cy-Gor, I would recommend an underbody immediately! Combining a small airdam connected to a slightly upward curved underbody panel (maybe with a diffuser too!) would work wonders for your SUV. I've spent a lot of brainstorming on how to improve SUV aero, and I'm pretty sure I've come up with some effective designs. If you ask nicely I'll draw something up for your vehicle and post it, and maybe you can build it!

Please don't hesitate to ask anymore questions!