Gear ratio to hit 20 mpg or close HWY 01 Yukon XL

[LordWayback]

I drive like 4 miles in the city a day otherwise I’m on the freeway what would be the best diff ratio to close in on 20 mpg (that’s known) 13.5 mpg combined is killing me with these prices averaging 5.50 for basic.
I don’t mind shelling out money or working on At least the rear diff but 7 mpg or a little less would make a huge difference I know the new trucks with AFM and highway diffs close in on 30 mpg Hwy.
(28.5 mpg registered on a factory turbo 4 cylinder Silverado with said gearing) hwy I think 20 mpg with a tune and diffs can be obtained without Active Fuel Management lifters. I spend 500$ or more per month on basic gas alone. So 20 mpg would drop me closer to 300 or less per month in fuel.

 

[LordWayback]

You may say “then why didn’t they do that from the factory” because of city mileage turning horrendous.

 

[LordWayback]

Yukon gear and axle sells a 2.73 which would obliterate all my city mileage but would be wayyy better highway

 

[intheburbs]

Probably easier to just find a junkyard 3.08.

 

[swathdiver]

I drive like 4 miles in the city a day otherwise I’m on the freeway what would be the best diff ratio to close in on 20 mpg (that’s known) 13.5 mpg combined is killing me with these prices averaging 5.50 for basic.
I don’t mind shelling out money or working on At least the rear diff but 7 mpg or a little less would make a huge difference I know the new trucks with AFM and highway diffs close in on 30 mpg Hwy.
(28.5 mpg registered on a factory turbo 4 cylinder Silverado with said gearing) hwy I think 20 mpg with a tune and diffs can be obtained without Active Fuel Management lifters. I spend 500$ or more per month on basic gas alone. So 20 mpg would drop me closer to 300 or less per month in fuel.

Which engine do you have and what is your gear ratio now? Which tire size are you running and what are they?

Slow down and let all the nuts fly past you wasting their gas.

 

[Doubeleive]

unless there is some reason you "have" to have a SUV then sell it and buy a 4-cyl economy car, these things are simply not fuel efficient, all you can do is gramma the hell out of it, basically be the slowest person on the road, do not accelerate, do not exceed 55-60mph, brake very early, draft whenever possible, do not sit and idle, turn off the ac, keep the windows up, tires inflated properly.

 

[intheburbs]

Slow down and let all the nuts fly past you wasting their gas.

I resemble that remark...

 

[Mudsport96]

Well even my wife can manage 15.5 to 16 with her driving, with the 5.3 and 3.42s at 55-60 mph. With lots of short trips between her 15 mile highway drive to work. So what is your setup and how do you drive?
Also a 2 73 will kill your mileage. Most likely unless you are running 75+ you wont be turning the rpms that you would need to stay in overdrive with light enough throttle to get better mpg. (Lugging the engine)
So how fast do you drive?

 

[Mudsport96]

Some examples of my rpms at speed vs a 273 gear.

 

[S33k3r]

The number one thing you can do is drive with a light foot. Number one thing. Now, in terms of technological solutions, these are the only things I can currently think of:

1) Drive with a light foot. It needs to be emphasized.
2) Convert to efans. They will bump mpg a tiny amount, but they will bump it up.
3) Tune for higher octane.
4) If you are wanting to regear for MPG, I suggest changing your cam so you can develop your torque as low as possible in the RPM band.
5) I have heard a turbo can help but, once again, you have to keep a light foot...
6) Reduce vehicle weight. Take out some seats, for example.
7) improve aerodynamics.
8) Not sure how you would do it, but you could also add active fuel management, theoretically. I mean, I don't advise it, but it would save gas.
9) By a cheap, fuel efficient beater for daily driving, and keep your Yukon for fun. And the beater is likely cheaper than most of the above.

That's all I can think of. Good luck.