Improve Gas mileage question....

[Cobaltdairy]

I got my 03 yukon not a xl or suburban length and it got 15.4mpg when I got it 2 tanks later it got 12. 4 Coils tested bad or week Plugs were red and melted tips down and ngk r plugs the guy said he put in but ya don't trust used vehicles much anyway . So it missed and run ruff and I decided to try what I've done to other vehicles that has proven to work but I had to test different plug gaps, I tow , play around race it, daily driver grocery getter. But here is what I have done so far maybe it'll help some one or get input to help me . All mods have 1 month of testing and so far so good but a dyno tune will get all I can out but I'm waiting to more parts on for . So parts on now are
Xyz tuning 4" intake system
Maf screen cut out
Ls6 coils I had
Ngk v-power plugs ( 0.44 gap )
10.4mm wires
Tb coolest bypass
Ported the Tb
Smoothed intake manifold and head runners
Cleaned every vent or module top to bottom
True dual exhaust to super 40s dumped before axle with 2.5" pipe cats back
New low drag wheel bearings front and back
Has 285/75 6 ply bald tires on it now that rim and tire weight is from 56 to 58lbs each by weighing all 4 individual

Getting 19.3mpg highway on a 50mile test run on the 4 lane and just everything from small town to hwy and home driving I'm at 17.4mpg. So I think that's pretty good but shooting for more after dyno tune.

Parts that I'm waiting for to arrive are
Cam kit, .625 duration springs ect.
1.7 roller rockers
42lb injectors
Trick flow heads
Hooked shorty headers
2500 stall
Trans break
Msd intake manifold
Electric fan conversation
2" wheel spacers
New tires
Wheels
Borla stinger mufflers
X pipe
Should be in and onto tune early october
Then the body shop uhhhh!

Compression is 5-11lbs under factory which is reallt good if it has the 180k on the 5.3 in it so just putting on what I can swap to a 6.2 later haha engine runs and drives smooth as can be and raps amazing so far hope this helps or any sudjections to squeeze a little more mpg out . For this 5.3 I'm hoping long shot for 21 mpg hwy and 350-360whp ish. If I forgot something you want to know on let me know

And
Castrol edge 5-30 oil
K&n oil filter

 

[08HoeCD]

I bought my Tahoe with the full and complete understanding that its fuel economy will roughly average 15 mpg, but that's the price I pay for having a big, comfortable, brute that I can haul people and cargo in.

I'm opposed to spending a dollar to save a dime, so I don't waste my time investing money into tunes, exhaust, CAI, etc. Considering what it costs to purchase & install all of that, even if my fuel economy goes from a rough average of 15 mpg up to 20 mpg, which represents a 30% fuel economy increase, I'd probably be spending $1,500 but would save only about $350 (or less) per year in fuel cost, or roughly $30 per month. It doesn't make sense.

 

[Knope]

I bought my Tahoe with the full and complete understanding that its fuel economy will roughly average 15 mpg, but that's the price I pay for having a big, comfortable, brute that I can haul people and cargo in.

I'm opposed to spending a dollar to save a dime, so I don't waste my time investing money into tunes, exhaust, CAI, etc. Considering what it costs to purchase & install all of that, even if my fuel economy goes from a rough average of 15 mpg up to 20 mpg, which represents a 30% fuel economy increase, I'd probably be spending $1,500 but would save only about $350 (or less) per year in fuel cost, or roughly $30 per month. It doesn't make sense.

I completely understand where you're coming from, but I would HIGHLY advise, at the very minimum, a tune from BlackBear. On top of that I'd say get the Air Raid Jr. MIT. Those 2 things alone will yield the best results in all around economics/performance and it'll cost you less than $400 total. Both are easy DIY projects

 

[08HoeCD]

I'd do it for performance only. But I gave up being a leadfoot when I sold my Challenger.

In terms of fuel economy, I feel better off using common sense and simple, prudent measures: drive her easy, keep tires correctly inflated, keep vehicle properly maintained---you know, things I'm going to do anyway rather than dropping cash on mods.

 

[shakedown067]

Best thing you can do is run a taller than stock tire. Didn't see what size wheel you are running. I averaged 18.6mpg (80% interstate) over a 2000 mile road trip with a high of 20.2 in my Suburban. Must have had a nice tail wind, cause I was running 80+. I saw the most HWY MPG improvement when I jumped to a 285/45/22 (68lbs wheel/tire).