I have had my car for a week and about 400 miles. Started with a full tank and a reset computer. 1/2 Tank refuel and the MPG reading was 19.7...RESET the computer and filled up, now it is reading 18.6MPG. Of those 400 miles, approx. 40 miles was highway. I haven't attempted to drive the car in a "gas-saving" way at all. In fact, I have run it hard through 3rd gear about 5 times while breaking it in. Under normal driving conditions, I shift around 2500 rpm. This may seem low to some people, but this car has no problem with this shift point, and you will be able to talk on the phone reasonably. So far, i am very happy with the gas milage my 05 Mustang GT is getting (especially compared to my 03 Hemi-Ram 1500). For those that are getting not-so-good gas mileage, I can only assume you are driving the car harder than you think. Different Ages lead to Different Perspectives; I am 33 years old and believe I know the difference between "normal driving", "sporting driving" and "racing". To get the advertised 17/25 MPG, just drive normally. I'll repost if anything changes in my experience with gas mileage on a Mustang GT, now that I'm almost over the 500-mile-mark, I'm guessing i will fall into the "sporting driving" category

 

The computer is not reliable or accurate, given past performance. To be sure of your mileage, divide the number of miles driven by the actual gallons used (from fillup to fillup) and that will give you the actual MPG.

I've had mileage computers on various vehicles and they are notorious liars.

Get back to us when you calculate it out and let us know what you're getting. You very well could still be the MPG king - but you have got to figure it out using actual gallons used for the actual miles driven; not what the computer is 'guestimating'.

 

I just filled my tank last night for the first time. I put in 18 gals., and had 180 miles on the clock, so I got 10mpg on the first tank.

 

You need to do it on the next fill up

 

The computer has always been within .5MPG for me. Usually it's within .1 or .2 and I'm actually beginning to trust it as the amount you pace in the tank veries from fill-up to fill-up. I got 17.3 on my first tank, the last 2 have been 20 and 22, but those include a good bit of highway driving. I'm very happy.

Jason

 

The computer is quite accurate. After 4 tanks I stopped double-checking the numbers.

As they say at the stock broker: "Past performance does not guarantee future results".

 

The computer is quite accurate. After 4 tanks I stopped double-checking the numbers.

As they say at the stock broker: "Past performance does not guarantee future results". [/b][/quote]
That may be - but to be absolutely precise, do it manually.

The computer is not measuring the volume of fuel that goes into the engine - it is based on calculated volume using the tank capacity. Also, if you top the tank off one time and then don't top it the next time, you will get a variance.

It may seem accurate (and easy) to pull up what the computer says but doing it manually, fillup to fillup, is the only accurate way to determine your mpg.


Using the "Past performance" line, that is also true of what you are experiencing right now, isn't it? Just because it was reasonably close before, how do you know it still is since "Past performance does not guarantee of future results"?

Call me obsessed, but I want to know my mpg based on actual amount of fuel used divided into actual miles driven. I do not trust a computer to guestimate it for me. "Close" is not accurate enough for me - I want it to the tenth.

 

[I just filled my tank last night for the first time. I put in 18 gals., ]

How is that possible when every 05 GT on the planet has a 13 gallon tank......either you have a dual tanks or are from another planet!!!!!!

 

Believe the '05 holds 16 gallons.

 

I have now gone through 5 tanks of gas. I know that some of the computers are messed up regarding mpg so I also calculated it myself and what do ya know....my car is bang on. My calculations and the computer both show I am getting 18.3 mpg which is better than the 16.8 mpg when I picked it up a few weeks ago.

 

Someone posted that when they did highway of 55-60mph, they got around 22mpg...

 

I also calculated my gas mileage manually for 3 tanks and found the computer to be very accurate. I am getting around 23 in a V6.

 

Whoops, sorry, it was 14 gals.

 

Is that how your 2005 Mustang works? Because MINE doesn't work that way.

The computer is measuring the fuel consumed (which it knows precisely) and displaying it in 0.1 gallon increments.

I think you are confusing the mistakes that people make (dividing the miles driven by the tank size) with the way the computer is doing it.

Call me silly, but the topping-off scenario you described measures accurately ONLY if you are topping it off exactly the same, every time. And guess what, due to variances between pumps, that is unlikely.

The fact that I've verified my computer against all 4 fillups, and it is SPOT ON, leads me to believe that the computer is accurate.

How many tanks have you put through your 2005 Mustang?

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Some computers may use tank volume, I don't believe the 2005 Mustang does. I believe that it taps into the OBD-II data. Why? Because my "fuel used" doesn't change when I park on a hill. If your version of how it works is correct, it would change when parked on a hill.

 

I'll second Bill on this one. The cars computer seems to be doing a better job of tracking fuel used, better than I could by tracking fuel loaded into the tank. Sometimes I top off, other times I don't. Regardless, there's no way for me to know exactly how much gas I'm putting in to ensure thatI'm filling it to the exact same point each time. I may double check the computer periodically, but I have almost complete trust in the computer now.

Jason

 

madhouse- Did the dealer put in 11 gallons? I thought thats about what they put in, and if so you should have gotten about 16.36 mpg. 180/11=16.36...

Not too bad for the first bit.

 

Bill, no flames here, ok? IF what you say is true - that the computer measures the actual fuel consumed accurately, then I will agree that the overall mpg can be fairly accurate.

But you also have to agree that to be accurate, the absolute accuracy of your fuel consumption measurement device and the measurement of distance driven will be the determining factors of the accuracy of your mpg.

"How many tanks have you put through your 2005 Mustang?"

None - I have not bought mine yet. Was that a dig? I hope not. But, I will be buying one very soon. But one need not own something to be able to understand how it works, right?

HOWEVER - I have had numerous other vehicles that read out digitally the MPG in average MPG as well as instantaneous MPG and they were not within a tenth of actual mpg. Usually, they were lucky if they were within even 1-2 mpg's.

Perhaps the '05 Mustang has a much more accurate fuel metering system (I would hope it would given the amount of advancement we have seen in electronics and computerizatoin). I never said that it wasn't - only that to be completely accurate and thus assured that your MPG is right, it is usually and historically has always been far more reliable to divide the miles driven by the gallons consumed and therein will be your actual MPG.

Sorry if you took it personally.

One other question - Does the new Mustang have a "Distance to Empty" readout on the display? IF it does, then it is indeed measuring tank volume from the fuel gauge. There is no other way that it can determine "Distance to Empty" unless it measures the volume remaining in the tank and this is the style of measurement I have seen before.

However, if it does not have that display, then it must only be reading the miles driven, the speed of the car, the rate of consumption over a given time, and the volume of fuel consumed to be able to accurately display MPG.

Not owning an IUP equipped '05 (yet), I do not know the answer. Does it?

So, I think we agree that determining MPG by the 'old fashioned' figure-it-out-with-gallons-and-miles method is indeed accurate. Having not had the chance just yet to run some tanks for my soon to arrive '05, I can't answer as to the accuracy of the computer. But from what others have written here, it appears to be far more accurate than what has been available in the past.

Enjoy your Mustang, Bill. I will certainly enjoy mine.

 

I'm not sure. It was full when I left the dealership. Could be, though...

I'll get a real reading next time to the pumps.

 

I'm still fairly amazed with everyone's facination over MPG with this car. If you want MPG, buy a Focus, not a 3,600lb V-8 powered Mustang. It flies right in the face of fuel efficient.

 

My adverage mileage in my GT, manually computed is 18.22 city
I ran moderately hard between 35 and 100miles on the odometer

250 miles on odometer now