I've only had my little 14 mustang for about 6 months. But I'm only getting about 10 to the gallon! wth??? anybody got any ideas? I'm even thinking about trading her in.

 

That seems extremely low. My ProCharged 2013 5.0 gets much better than that. How are you checking mileage?

 

Just to get this out of the way:
"If you care about gas mileage, you shouldn't have bought a Mustang"

OK, now we can get back to the OP's question and nobody else will need to say that

Yes, that does seem quite low. First make sure you have reset the mileage computer. Preferably, reset the mileage counter at the same time that you fill up the gas tank, and get ready to calculate the mileage the old fashioned way.

(In case you are not familiar: you write down the odometer reading when you fill the tank; next time you fill the tank, you record the odometer reading and the gallons to fill; the gallons to fill is the amount of gas you used and the difference in the odometer reading is the miles you traveled; divide miles by gallons to get miles per gallon)

Once you are confident that the mileage is reasonably accurate, so you won't be chasing phantoms, then look at the potential causes. First things are standard maintenance items: replace fuel filter, replace or clean air filter, clean mass air flow sensor, confirm oil is fresh, etc.

 

auto trans or manual??

 

Follow Bert's suggestions first. That will let you know if your computer is giving you true readouts.

Does the car have a tune? Does the car have a supercharger? Give us some setup info and we can give you more info back.

 

ok, yeah i should have said more about her....sorry. First i'm 59, and don't really have that much of a lead foot, I only drive her to work and around town, when I do go out of town, which is only about 100 miles it take almost half a tank! She's a 2014 mustang, not a GT. She has 50,000 on her already but they told me that's like " just getting broken in". The computer tells me at a full tank I only have 235 till empty......is that normal? I've been going by the computer and it tells me I'm getting 19.9. But I have to fill up every week, So I starting to think the computer is full of ****!!........Thanks for replying.......

 

maybe unhook your battery for a few minutes to reset everything. Maybe the previous was a lead foot.

 

You can't judge mileage by looking at the gauge. The only reliable way is to log your miles between to full tanks: Fill up, note mileage (or rest trip odometer). Drive until you need gas and fill it up again. Note mileage (or look at trip odometer). Miles/gallons = your mileage for that tank. Using the car's MTE estimate or looking at the gauge will not be accurate.

 

I wonder if she is only drawing from one tank? There was some problems awhile back with this. There are two tanks due to the driveshaft location.

 

wth, i didn't read anything about 2 tanks???????? you guys are messing with me huh????

 

Here is the tank you have. It is connected at the very top but it requires two fuel pumps. The driveshaft runs through the middle between the 2 sides. When you fill how many gallons? I would think if your getting only 10 mpg that would be extreme and that could be hard on the catalytic converters.

https://parts.lakelandford.com/p/For...wd=&origin=pla

 

Are you using E85 gas? Did you buy the car new? Is it a GT?

 

I thought I was bad getting 16-17

 

And I've been disappointed that I rarely get more than 30 mpg out of a tank.

 

The only time I get mileage that bad is when I am at the track. How hard are you driving?

 

235 miles till empty is 14.6 mpg. Still pretty bad . I have 3.73 rear gears in my v6 and get 19-21 mpg, all in town driving. I also get on it here and there and not trying to get good gas mileage

 

How are you driving? Mostly highway, city? You say it's not a GT?

My gas mileage is pretty bad too, I get from 13-15 depending how I drive. I'm in New York City, even when I'm on the highway, it's not really highway driving. It's always stop and go, slow, fast, slow, changing gears, I'm never able to cruise at a constant speed for more than a few minutes to get actual highway mileage.

 

18-20 mpg mixed driving sounds about right. I get that in my 2013 GT Auto. Usually 18 mpg.

I was getting closer to 23mpg driving highway San Francisco to San Diego.

 

I've never gotten worse than 18 on a tank with my GT, and that tank included 45 minutes of track time at Road America.

Your car is FAR past break-in time so that's not it. My experience driving an automatic V6 Mustang like yours resulted in 25-28 MPG consistently.

As for not being able to trust the onboard computer, that's a bit extreme. In my experience, the onboard computer is within 5% of what I calculate myself.

 

What kind of driving do you do otherwise in your GT? When do you shift? Do you stay in a higher gear most of the time? Even with mixed city/highway, I'm only getting 17-18mpg, 13-15 all city. The best I ever had was when I drove from NYC to DC all highway, about 24mpg.