5.3L V8 that is...getting 16.5-17.5 max highway miles per gallon:

to anyone who may consider trying and I can help, here it is.

03 Yukon XL 4x4 that I did not buy for fuel efficiency, but have tried a few combos to try to stretch the gallon on the same 1000 mile round trip I make on a regular basis. I will say that w/ some dyno or software tuning these mods may help, but I don't have access so here's what didn't work.

-tornado air -no change with or without, had a free one to try thankfully
-gibson exhaust -no mileage benefit over stock, just got a headache
-magnaflow -ditto, but sounds worlds better than the god-awful gibson
-lucus "better mileage" additave, no benefit
-K&N Cold Air Intake -made the throttle snapier, but no mileage benefit

The only thing that helps...after spending too much money trying is MICHELIN LTX M/S regular load tires -least rolling resistance of any tire I'm aware of and NO 20's. Heck, I lost mileage going from the stocker 16s to the 05 17" take-offs, much less going to 20s. Get you a k&n drop in filter and call it a day.

I change the exhaust on everything I own...and have always without exception had an increase in power and mileage. The yukon had no mileage benefit whatsoever over the stock exhaust.

 

LOL. Wonder how many people you will confuse with the thread title and think that you are getting 5.3 mpg.

ps. Look into getting a custom tune.

 

+1 on the custom tune. PCM tuning will increase power output at given throttle position so that less throttle is req'd. That's my theory and I'm stickin' with it.

 

hah i was confused..i was going to say wow thats pretty shitty.

 

consider a taller and narrower tire. Handling will be worse, but ride comfort and mileage should be improved. Pump them up just over the factory air pressure rating.

Consider a lower front airdam and blocking off part of the grille.

You've got a roof rack, right? Do you ever use it? If not, take it off. If so, move the cross supports all the way to the back.

 

And I'm jealous of your cars! A CTS-V and THUNDERCHICKEN! I loved reading about that car when Hunkins owned it.

 

headers with custom tune is a better combo I say. But tune does most of the work.
And you can reduce some resistance by throwing that tornado away.

 

HA, thanks. Yeah, in the CTS-V I get 26.8mpg on the interstate. That is with the help of HP Tuners and a friend of mine. We were going to do the Yukon but haven't gotten back together as he lives a bit away from me.

Thanks for the comments, the bird is fun for sure! I kept up with Hunkins fairly regularly for years after I bought the car.

 

this sounds lame i know, but I live in the country and was coming back from town the other night and was in no hurry at all, and was just gonna see how it turned out by driving no faster than 50mph. When i got home i checked my mpg and was gettin 28. Thats the best gas saving tip i got, even tho its so hard to do its ridiculous.

 

not crazy at all...and works in every vehicle I own except the yukon. The last 100 miles each way on my recent road trip is non-interstate and 60mph max. Per the instant economy reading on the display I get no better economy between 60 and 80. As a matter of fact at 70 the power/torque curve must really suck because it doesn't pull well up hills and such, but at 80it will stay dead on w/ no down shifting or anything.

I know this gets discussed a lot, but there's always good info that surfaces.