I have owned my mustang for almost a month now... it has 5000 miles on it (purchased as the Dealership Demo). I have posted multiple posts about bad MPG, and trying to fix it. Everyone seems to say driving habits. Mine are fine, I have asked numberous people who rode along with me, and verified that. Today i drove from Tampa to the Beach (about 25miles) and back. About 10miles were in bumper-to-bumper traffic, but the rest were driving on the interstate around 50-60mph.I also drove 13miles of the way back with the vert down. I used up half a tank of gas on around 55miles total Anyyone else having this bad of gas mileage?

 

Are you sure you actually used 1/2 tank? Remember the instrumentation is far from accurate anywhere between full and empty. To use 1/2 tank in 55 miles is unheard of. Do you have a leak? If it's truely using that much gas I would imagine the back of your car would be covered with soot from running so rich.

 

The best way to check your MPG:

1. Fill up tank (all the way)
2. reset trip odometer to 0
3. drive around for a few day (at least 100mi).
4. Fill up tank again (all the way)
5. write down # of gallons it took to fill, then divide the miles driven (on trip odometer) by the # of gallons used.. this will be your accurate MPG.

By the way, if you only want to check your highway MPG, then find some open road (no stop-n-go traffic) and log 50+ miles only...pull of highway, fill up, and do the math. I've been logging this for a few months and I consistently am getting 17-18MPG city/around town driving, 19-21 city and highway miles, and 25-26MPG highway miles only. If you getting significantly less MPG, and you're not burying the throttle all the time, something is wrong.

 

I've been following your mpg threads and I am beginning to think something really is wrong. Even though you said you sat in a bunch of traffic, there is NO WAY your car should use 1/2 tank for 55 miles. That is about 6.8mpg (assuming 8 gallons used).

Any issues with the engine running rough, stalling, lack of power, etc? Have you checked your oil lately?

I would take it back to the dealership and see what they can do to figure it out. I don't even know where they would begin, but then again that is their problem.

 

Agreed. Short of a leak the only way to use that much fuel would be running SUPER rich. As I mentioned you'd have a lot of soot on your tail.

 

No Soot on tail... I clean the car every 2-3 days, and there is no built-up residue. I am not burning rich that I can tell, I should be able to smell it when the top is down. No leak, at least no signs of one on my driveway or in my garage, and gas tank is the same when i get in the car as when i left it.

 

That's amazingly bad mileage. I feel like I'm doing kind of bad on mileage and I'm averaging around 17-18! I would definitely take it to the dealership and see if they can uncover any problems.

 

Do you have the IUP with the info center?

If so, what does the "Miles to Empty" readout say when you fill up your tank?

On a fill up my readout usually gives a range of 290 - 310 miles to empty, depending upon my average gas mileage accrued.

What does yours say?

 

I never look at that thing the green doesn't match the blue gauges. I get about 16-17 ish and make no effort whatsoever to conserve gas nor drive on the highway to work(all back roads with great curves). Even on short highway stints I stay in 4th at 65mph. After a couple thousand miles I will probably start tracking it(by the tank fill/odo reading) periodically.

 

When you fill up the tank, does it take approximately the same amount as what the display says it used? If not, maybe there is a problem in the fuel useage sensor (or whatever it is that senses the fuel use).

 

Take that car to the dealer after you manually verify the mileage vs. how much gas you actually burned. It could be something as simple as a bad guage or sender unit. I drive 25 miles each way to work, 20 of it in bumper to bumper stop and go traffic, and I averaged 19.7 over my last 5 tanks and I make absolutely no effort to conserve gas, my wife would venture to say I do my best to rid the earth of fuel singlehandedly. My car isn't exactly stock either.

Verify your mileage manually, then drop the car off and say "fix it". That's what warranty's are for. If it's really a problem, quite wasting money and potentially causing damage to your car.

 

I wonder if the coolant temp sensor is off enough to leave the engine in open loop which might cause a over rich condition.

 

Schedualed a drop-off at the dealership on wednesday....will keep you up to date on what they will confirm...last time I took it in they said they can not find a problem. Hopefully this time they will fix it. After they fix I am going to put a CAI / Tune...and some GTA's on it to fully open it up. I don't want them to have any reason to blame this on Mod's when the problem was there from the beginning!

 

I'm getting 15.8 city and 27.3 highway. Reset your guage before getting on the freeway and see what it reads.

 

I wasn't able to get the IUP...so all I have is the stupid odo. not trip computers to tell me Avg mpg, Miles to empty, etc.

 

I'm getting about 19 in the city and about 26.2 on the highway. Right now, I'm sitting approximately at 24.1 miles per gallon in my v6 which to me is great. If you are getting 55 miles on a half tank of gas, there is seriously a problem. Even when my car went in the shop (with nearly a full tank of gas) for repairs, then I picked up her about a week later...I noticed that my car was sitting at 2.5 miles per gallon when I started her up. I don't know how long or how often they started her up and left her running while they were doing what they had to do. In any case when I started driving...the miles per gallon just started to go right back up into the low 20s in the city once I started driving for 10 - 20 miles. Sounds like a problem to me. Definitely keep us updated.

 

Well in that case heres a website that will track mileage for you. All you have to do is enter everything in everytime you fill up. I know its not for your area but it will still work.

www.fresnogasprices.com

its under fuel logbook.

 

There should be a toggle switch, push button (or something) on your Mustang to switch between the odometer and the trip meter. Trip computer only tells you how many miles you driven on that session (until you reset it, if you do)...the Interior Upgrade Package adds all the other "geeky" stuff such as MPG bar, Average Speed, Average MPG, Trip Timer, etc. Since I love all that gadetry, I had to get a 'Stang with the IUP but a trip computer is very basic, should be something in there to let you switch between the odometer and the trip meter.

 

I got 3.6 mpg on my first fill up (standard way of calculating it). The GT can suck down gas very quickly in heavy stop and go traffic.

 

My average mileage over the last 24,000 miles, according to the computer is about 18.5 MPG.

You may have only been in ten MILES of bumper-to-bumper. But the real question is how many minutes or hours you sat in the b-to-b traffic with the engine idling away. If that ten miles took two hours (been there and done that too), that is more significant than if that ten miles took 15 minutes.