Poor gas mileage question

[ForYourOwnGood]

I average 290-300 miles per tank with a supercharger... around 20mpg

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[Braski]

I average 290-300 miles per tank with a supercharger... around 20mpg

Forget the mpg and start enjoying that supercharger!

 

[Braski]

Good evening,
I recently purchased a used 2017 mustang GT from a dealership. It has about 1500 miles on it. The modifications that it has are a Roush cold air intake, Roush axle back mufflers and a Roush H pipe. I just had it tuned and it is making 426 HP. It was making 378 before the tune. It is running smoothly but the gas mileage is deplorable. It is registering about 16 MPG overall. The SCT tuner that was used to load the tune did not throws any codes and the gas mileage was the same PRIOR to the tune. My last S550 got much better mileage and I relaize that this mileage is grossly abnormal. Any feedback is appreciated.

Thanks

Stock my car averaged 16.9, with the pp2 I averaged 16.2 and with my EB-2300 I'm currently at 10.8! The faster the car the faster I'm willing to to push and pay for the fun button!

 

[ForYourOwnGood]

Forget the mpg and start enjoying that supercharger!

Unfortunately I can't ignore it completely as my trip to work is 42 miles one way. I have to fill up every other day.

 

[HiTekExec]

Good evening,
I recently purchased a used 2017 mustang GT from a dealership. It has about 1500 miles on it. The modifications that it has are a Roush cold air intake, Roush axle back mufflers and a Roush H pipe. I just had it tuned and it is making 426 HP. It was making 378 before the tune. It is running smoothly but the gas mileage is deplorable. It is registering about 16 MPG overall. The SCT tuner that was used to load the tune did not throws any codes and the gas mileage was the same PRIOR to the tune. My last S550 got much better mileage and I relaize that this mileage is grossly abnormal. Any feedback is appreciated.

Thanks

2019 GT PP A10 loaded, avg just under 22, usually in sport+... all fine by me... I didn’t buy an Orange Fury GT for its economic MPG
Anytime I see lower MPG I attribute it to my right foot.

 

[Ebm]

You bought a GT what did you expect? 426 hp, 16 mpg isn't so bad. My Hellcat averages 10

This.

The Mustang isn't a lighter weight and more aerodynamic Corvette, nor is it a Prius. If this is your first performance car, I'd say this is a welcome to the world of high performance cars.

Your right foot controls how fast you go and how much mileage you get. If you want better mileage, accelerate slower and drive like granny(go 5 or 10 mph below the speed limit). If you are expecting 30 mpg, park the GT, because it ain't happening.

 

[frank s]

Other than the customary depth-of-accelerator determinants of MPG, there are a limited number of influences. Fat tires? Underinflated? Mistaken axle ratio setting? Mechanical drag in the wheel bearings, brakes. Ugly, slow color?

A rigorous examination of all those and similar whatever else might be present should reveal some contributors.

My '18 PP1 10-speed has delivered 19.9 overall under conservative conditions. Yours might just have all the MPG tolerances in the wrong direction.

I'm guessing Fat Tires.

 

[pctek]

My daily driver is a '15 GT Premium. It rarely sees highway miles. Work is 10 min from home. I get 13mpg. When I take it on a highway run I get 23-24mpg. The odd thing I have found is that once the fuel gauge hit 1/2 tank, the mpg doesn't change more than a point or two. I think the algorithm used to calculate mpg stop "learning" after 1/2 tank is used. My info center is constant in that the engine on hours is just over 12 hours and my total miles is 210.

 

[Genxer]

My '15 with a tune and CAI was getting 17-18. Didn't suffer much from having a mild tune. Aggressiveness of the tune, aero modifications, tire pressure, driving habits... it all comes into play.

 

[Deleted member 35786]

The OP did not state his location either. Is he in Colorado/Utah etc.. driving at a higher altitude which can greatly affect mpg. Also just a gee whiz but does the convert get worse mileage compared to hardtop? Aerodynamics in play perhaps? And 3.73 gears are low.. what is your rpm at say 60mph? The tune might have affected your mpg at some point as well.

 

[Commbubba19]

17 GT auto 3.31 gears. At 75mph i'm spinning 2250 rpms. Instant on flat interstate will give me almost 27-28. I average about 24-25mpg per tank. Mostly interstate. I have 20x10 square wheels / tires. Lowered, and Ford Power pack 1 installed.

 

[Deleted member 35786]

17 GT auto 3.31 gears. At 75mph i'm spinning 2250 rpms. Instant on flat interstate will give me almost 27-28. I average about 24-25mpg per tank. Mostly interstate. I have 20x10 square wheels / tires. Lowered, and Ford Power pack 1 installed.

That is high.. Did you adjust your AFE bias? Ford computers tend to read 1-2mpg higher than normal. Mine use to read that but now its 24mpg at 80mph/2100rpms with factory 3.15 gears on an Auto.

https://www.mustang6g.com/forums/threads/how-to-adjust-your-indicated-average-fuel-economy.48903/

 

[MikeHTally]

That is high.. Did you adjust your AFE bias? Ford computers tend to read 1-2mpg higher than normal. Mine use to read that but now its 24mpg at 80mph/2100rpms with factory 3.15 gears on an Auto.

https://www.mustang6g.com/forums/threads/how-to-adjust-your-indicated-average-fuel-economy.48903/

Mine sure does. I've not owned a car that wasn't very optimistic on its mpg. The last tank was 24+ according to the computer. Actual was < 22; mostly city but some interstate.

 

[bnightstar]

For over 6000 KM my car (2017 GT 3.55 PP MT82) average 15.5 l/100km or around 16 MPG (US) on highways and trips it get's down to 10 l/100km or around 22 MPG(US). My car is bone stock and new and I don't push it hard. So your fuel consumption seams normal to me.

 

[Ronin47]

Looks about right

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