I'm not exactly sure how to word this, so I'll give it a try and hope that the words I'm trying to get out come across correctly.
On the Mustangs that come equipped with the Interior Upgrade Package, it includes a nifty little gadget in the gauges that computes the average miles per gallon, distance traveled, time traveled, average speed and number of gallons used. I've found everything listed on the display to be pretty accurate. I've been measuring my mpg's and it's been right on cue with what I read on the display whenever I check it. My question however, concerns the number of gallons used indicator on the display. I know that from the manufacturer our cars are designed to hold approximately 16.0 gallons of gas, however, what if one is able to put more than 16.0 gallons in the tank? Would the extra gas in the tank be factored in by the car's computer or will it read and compute by the first 16 gallons used in the car. Example, last night I filled up at a gas station and by the time I was done I had pumped exactly 16.600 into the tank. Now as I drive along in the future and use this gas, will the computer in the car determine the amount of gas used by the first 16 gallons or will it factor in that extra .6 of a gallon I was able to put into the car last night. Thus far, I've been filling up my car within the last 5 miles of gas I have left, according to the computer, and I haven't chanced it on going farther once I hit "E" by the computer's standards. So I'm wondering if I pumped 16.6 gallons like I did last night, do I have 16.6 gallons to use or will only the first 16 gallons be recognize by the car's computer.
I hope that makes sense and didn't come across as jumbled as I thought it would.
I got a bad tank of gas, think it was half water , ran it until the display said 5miles left. Had a can of good gas to refill it with when it ran out. So I thought it would only take a little while to run out.
It ran for 4 hours idling in the driveway for it to finally run out. I'm pretty sure I could have driven alot more than 5 miles.
I don't know how the computer will read the mileage but i don know if your manual says that you have 16 gallon tank that you in fact have like a 17.25 gallon tank. Its a federally administerd thing. But i have many times before taken a lot more than my tank can hold. And then i wonder if the gas station wasn't downhill, if i would have ever made it.
I don't think the computer knows how much gas you actually put in the tank when you fill up, I think it comes up with the gallons used by your average mpg and how many miles you've travelled.
The computer counts the number of times the fuel injectors fire to estimate the fuel consumption. It's pretty accurate but not perfectly accurate. I agree on the 17+ gallon tank. You have to consider how much fuel is in the lines and how much you have 'over-filled'.
I have several times driven well past "0 miles to empty" with the most being about 15 miles past that point, yet I have never been able to put in more than 15.9 gallons of fuel.
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2005 Mustang GT with 04 Cobra iron block, 300 ci, Kenne Bell 2.6l twin screw, P&P S3 Heads, SS valves, Comp S3 cams, Currie 9+ 9" rear end and DS (coming soon), Hurst shifter, BMR K-member, A-arms, LCAs & UCA, JBA long tubes & mid-pipe, Accel COPs, GT500 fuel pumps, much more... 659 RWHP, 598 Tq @ 12 psi & 5800 RPM
It sounds like your gas station is ripping you off and charging for gas that has not been put in. I've been down to E a few times and at best I put in about 15.2 gallons.
Check out the stations calibration certificates
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Peace.........The MadMan
06 Premiuim GT | Tungsten Grey | IUP | 5-speed manual | Dark Charcoal Interior | Full Tint | American Thunder FlowMaster axle-backs | 18x9 Black Bullitts | Kumho 255/45R-18 | Hurst shifter | various MGW goodies | Roush pedals | Member SDMC
"I closed my eyes, held my breath and then everything went black."
- Richard Petty - (About his 1988 Daytona accident)
You could just drive until it runs out then call up AAA and ask them to fill you all the way up and see how much it takes. But i am sure that the computer isn't stupid when it calculates the mileage and gas consumption. Otherwise ford would have gotten rid of it.
You also have to take into consideration that your engine lets say 4.0 for the sake of arguement. That 4.0 has gas inside of it, so there are many variables to take into consideration.
the key is to try and not go to the cheapy gas stations cause you run a higher risk of getting watered down gas.
I too have run 10 miles when the computer said "0 miles to empmty" and still only put 15.6 gallons in it (I was gettign 16.5 mpg). I have several Fords, all of them have this computer feature. I have found the mpg is very accurate, but the "miles to empty" are conservative. Like on my F-150, it said I had 31 miles to empty; it has a 30 gallon tank and I was getting 17.5 miles to the gallon, yet I was only able to put in 26.7 gallons. I think the computer may have a default setting in hopes you fill up orior to "0 miles to empty" so you do not run out fuel.
I too have run 10 miles when the computer said "0 miles to empmty" and still only put 15.6 gallons in it (I was gettign 16.5 mpg). I have several Fords, all of them have this computer feature. I have found the mpg is very accurate, but the "miles to empty" are conservative. Like on my F-150, it said I had 31 miles to empty; it has a 30 gallon tank and I was getting 17.5 miles to the gallon, yet I was only able to put in 26.7 gallons. I think the computer may have a default setting in hopes you fill up orior to "0 miles to empty" so you do not run out fuel.
Interesting, mine has been accurate. Last time I ran it to about 45 miles remaining and put in about 13.8 gallons. Assuming an actual 16 gallon capacity, the 20.5 mpg for a tank of all commute miles was spot on for the remaining 2.2 gallons in the tank.
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Black 2006 Mustang GT Premium Coupe | Interior upgrade package | 18" 'Torque-Thrust' style wheels | Shaker 1000 | T3650 | Side airbags
It sounds like your gas station is ripping you off and charging for gas that has not been put in. I've been down to E a few times and at best I put in about 15.2 gallons.
Check out the stations calibration certificates
I am glad someone else said it. I hav enever been abel to get over 15 gallons in my tank, and thats when it said I had 50 miles to empty and the gage was very low
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2006 Mustang GT in Torch Red
C&L Intake, Evolution Performance Tune, Borla Axle Backs, Hurst Shifter, 4.10's, JBA Long Tubes, Prothane Engine Mounts, Steeda UDPs, FRPP Charge Motion Delete Plates
Well in my first two fill ups after initially having the car I got a little over 15 gallons (with a little topping off - 2 clicks). Now at each fill up, I'm getting any where between lower to mid 16 gallons in the tank, with mild top off (tank clicks off twice). So I don't know if it was a breaking in kind of thing or something else. 16.6 gallons was the most I've put in the Mustang thus far and according to the on board computer I only had 5 miles to E...but 8 days prior to that I only put in 16.1 gallons with only 2 miles E, so I don't know.
I had noticed however, that when I got down to my last 30 miles (or so) before E message, the estimated gas mileage reading started to double up (in some spots) on the number of miles I actually had left before E taking 2 miles for every 1 mile I traveled.
I've never taken my car to the 0 miles to E limit (been close) or beyond, and not sure that I actually would without someone there to give me gas, or without having a gallon of emergency gas in one of those little red tanks inside the car in case the car shut off from the lack of gas in the tank..
Question on Gas Usage/Mileage. 
, ran it until the display said 5miles left. Had a can of good gas to refill it with when it ran out. So I thought it would only take a little while to run out.
