DECLINE IN GAS MILEAGE

[H_Cons]

I HAVE A 2016 MUSTANG GT PP. I JUST HIT 14K MILES THE OTHER DAY. FOR THE PAST MONTH OR SO I NOTICED A DECLINE IN MY GAS MILEAGE. I TYPICALLY DRIVE THE STREET AND A LITTLE FREEWAY AND I AVERAGED ABOUT 14-15MPG. NOW THE PAST MONTH MY AVERAGE MPG HAS DROPPED TO 10-11MPG. IM NOT DRIVING IT ANY DIFFERENT THAN BEFORE AND I HAVENT DONE ANY MOTIFICATIONS THAT MIGHT CHANGE MY GAS MILEAGE. I DIDNT GET A V8 FOR GAS MILEAGE BUT I THOUGHT THE SUDDEN DROP WAS STRANGE. HAS ANYONE EXPERIENCED THIS BEFORE OR KNOW WHAT IT COULD POSSIBLY BE?

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[Jiki05]

When you read that to yourself does it seem like screaming? Anyways, I drive mostly highway and I usually drive it like I stole it and still get 23-24 mpg and I have almost 50k miles.

 

[TheOilman]

2017 Manual GT PP averaged 17-19 mpg with occasional spirited driving...15-16 when its really hot and the a/c is blowing, best ever was 23-24 mpg on a long trip to the beach. Even off the bat your mileage is a bit low unless your right foot is fairly heavy. 93 octane? Any tune or mods? Last time you checked your air filter? Tire Pressure?

 

[Hack]

I think the problem is the motifications. Are you sure you aren't running AC or doing something different? It seems pretty unlikely to me that your fuel economy would decrease by ~30% with no changes. And 10 mpg is exceptionally low unless you are doing super short trips or really hammering on it. My best recommendation is to take it to the dealer and have them check it out.

 

[Benjj]

Have you been using your ac more? It’s summertime, there might be more traffic with ppl on vacation from school/work. maybe a combination of the 2.

 

[NoVaGT]

It's you, the way you're driving. Plus possibly running A/C.

Relax, THERE'S NO NEED TO SHOUT!!!!!

 

[sdiver68]

Many areas have Summer formulations of gasoline, not sure if that applies to your area or not. People have reported performance differences between formulations for years.

 

[w3rkn]

How are you determining your gas mileage.... ?

 

[johnscousin]

I'm experiencing the same issue at almost the exact same mileage on a completely unmodified car. My daily drive to work is 10 miles. The first 2-3 are done at a top speed of 35, while the remainder are interstate, running between 65-75. Yes the AC is on, but last summer my overall during the work week was more in the 16-17 range. Now at best my mileage is around 13.

Generally I am running Shell 93 octane with an occasional tank of Quik Trip 93.

jc

 

[PJR202]

How are you determining your gas mileage.... ?

I don't think it would matter, would it? Some feel the built-in gauge is inaccurate and some feel that doing the math at the gas pump isn't reliable either. But, if he's using the car's gauge he's still seeing a big difference. It's like using an inaccurate bathroom scale. It could be 50lbs off but if you go on a diet and lose 5lbs per that scale, you still lose 5lbs.

 

[Ebm]

.

I HAVE A 2016 MUSTANG GT PP. I JUST HIT 14K MILES THE OTHER DAY. FOR THE PAST MONTH OR SO I NOTICED A DECLINE IN MY GAS MILEAGE. I TYPICALLY DRIVE THE STREET AND A LITTLE FREEWAY AND I AVERAGED ABOUT 14-15MPG. NOW THE PAST MONTH MY AVERAGE MPG HAS DROPPED TO 10-11MPG. IM NOT DRIVING IT ANY DIFFERENT THAN BEFORE AND I HAVENT DONE ANY MOTIFICATIONS THAT MIGHT CHANGE MY GAS MILEAGE. I DIDNT GET A V8 FOR GAS MILEAGE BUT I THOUGHT THE SUDDEN DROP WAS STRANGE. HAS ANYONE EXPERIENCED THIS BEFORE OR KNOW WHAT IT COULD POSSIBLY BE?

1) All caps isn't needed. We are all civilized people here and can have a casual conversation without raising our voices

2) You sure you don't have 4 flat tires you are riding around on? Holy cow! 10 mpg...

3) Any check engine lights?

 

[tom_sprecher]

26 mpg on the highway is my average, but I drive 2-3 hours at a stretch. Before I accidentally reset trip meter 2, my overall since the day I bought the car was 21mpg. In town is around 15-16. 25k miles on the odometer and still on the original P-Zeros.

I feel the in town mileage will drop a bit since I installed the Borla S-type AB's. I can't seem to stop leaning into it for every damn shift.

Just out of curiosity what's you AFR at say 2200 rpm using cruise control on a straight, flat stretch of highway?

 

[w3rkn]

I don't think it would matter, would it? Some feel the built-in gauge is inaccurate and some feel that doing the math at the gas pump isn't reliable either. But, if he's using the car's gauge he's still seeing a big difference. It's like using an inaccurate bathroom scale. It could be 50lbs off but if you go on a diet and lose 5lbs per that scale, you still lose 5lbs.

It matters, because it determines how he is verifying his mileage.

Is he seeing how long he can go on each tank, then comparing it to the last tank..? Is he using the on board computer and using the instantaneous read out..? Is he using the average read out..?

Nothing matters in helping him understand his problem, until we can determine how he knows he is getting 10mpg...!

 

[PJR202]

It matters, because it determines how he is verifying his mileage.

Is he seeing how long he can go on each tank, then comparing it to the last tank..? Is he using the on board computer and using the instantaneous read out..? Is he using the average read out..?

Nothing matters in helping him understand his problem, until we can determine how he knows he is getting 10mpg...!

Maybe I shouldn't give him credit for doing a controlled study until he stops typing in ALL CAPS. ;)

 

[grabber yote]

I suggest a KAM rest.

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