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Gas mileage question


cobraetti

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  • 2 weeks later...

With as difficult as it is to fill the gas tank really full I dont know how anyone can be sure that the MPG calculator is not accurate. I have used the same gas station for years. Same pump, same position ect. When I fill the tank in a hurry it will take much less than when I do the slow fill and wait for the gas to show in the filler neck. Then rock the car and put a little more in untill the level is constant at the top.

Just not like the old days when a fill up was really full. Now days manually calculating the MPG is really difficult because of the way the fuel tanks & filler necks are configured. I gotta think that the car MPG calculator is more accurate than I could be.

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With as difficult as it is to fill the gas tank really full I dont know how anyone can be sure that the MPG calculator is not accurate. I have used the same gas station for years. Same pump, same position ect. When I fill the tank in a hurry it will take much less than when I do the slow fill and wait for the gas to show in the filler neck. Then rock the car and put a little more in untill the level is constant at the top.

Just not like the old days when a fill up was really full. Now days manually calculating the MPG is really difficult because of the way the fuel tanks & filler necks are configured. I gotta think that the car MPG calculator is more accurate than I could be.

 

 

I think it's alot easier than you are making it out to be. The way i fill all my vehicles is to let the pump run until it clicks off, wait a few seconds and then just barely squeeze the fuel pump so that fuel begins to flow, when it clicks back off I'm done. On my Edge when the low fuel message comes on I always get about the same amount of fuel in the tank when I fill up, the + or - 1/2 gallon isn't going to make a huge difference in mpg calculation. The idiotic mpg calculator on the dash is about as useless as the mpg estimator on the window sticker...isn't it funny how the mpg calculator and the mpg estimations on the window sticker are really close in real life.

 

Realistically this vehicle is good for about 15-16 in town and about 22 on the freeway at todays driving conditions. Now if you cruise at 55 mph on the freeway...which will make everyone extremely happy...you will get alot higher mileage.

 

JMO

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  • 2 weeks later...

I keep records on an Excel spread sheet. stats.gif

Since January 1, 2010 I have traveled 20082.00 miles and have purchased 931.096 gallons of fuel.

The average over 9+months is 21.568 MPG. This includes a Highway and City driving, obviously much more highway than city.

Highest was 26.06 MPG and lowest was 16.15MPG.

Greatest quantity of gas in one fill-up = 20.671 after 513.8 miles 24.86 MPG

This is averaged over 66 entries into the spread sheet and includes every weather condition imaginable (snow, rain, head wind, tail wind, 110+ heat and <10).

No jack rabbit starts, always anticipate stops and traffic slow ups, shift to neutral at stop lights.

2009 Edge now has 39135.7 miles on the tracker.

 

I'm trying to wear this one out so I can get one with the 3.5 EcoBoost. happy%20feet.gif

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  • 5 months later...
  • 11 months later...

 

When I had the stock 18" wheels I had 24.5 hwy, 18.5 city. now on 20" with 255/50/20 ist did pull the mileage down a little

22.5 hwy, just under 18mpg city. I'm not a redlight racer but I do drive faster then flow of traffic

 

Upgrading to larger wheels will kill your mileage because of the increased unsprung weight (more metal & more rubber) and the increased rolling resistance (wider footprint).

 

 

With as difficult as it is to fill the gas tank really full I dont know how anyone can be sure that the MPG calculator is not accurate. I have used the same gas station for years. Same pump, same position ect. When I fill the tank in a hurry it will take much less than when I do the slow fill and wait for the gas to show in the filler neck. Then rock the car and put a little more in untill the level is constant at the top.

Just not like the old days when a fill up was really full. Now days manually calculating the MPG is really difficult because of the way the fuel tanks & filler necks are configured. I gotta think that the car MPG calculator is more accurate than I could be.

 

There is a built in volume to the fuel tank to allow for expansion. If you fill-up using your slow/rock'em/sock'em method and fill until you see it at the top, you have not left enough room for heat related fuel expansion.

 

Now do this on a HOT day and then let it sit in the sun you are asking for trouble. Liquids are not compressable at all. That is why any time you see a bottle of liquid there is always a space for expansion.

 

Pumping gasoline stored underground that is cool into your vehicle your way does not leave any room to expand. It may take a while before something in the system weakens from the repeated expansion stressors but someday something will give somewhere--like a gasket or a weld seam, maybe split the fuel line or rupture the fuel filter. Can't say because I am not an engineer but I've taken several physics courses and I have slept at numerous Holiday Inn Express motels!

 

As far as the manual calculation, it's the average of many fillups that will give you a truer fiqure. Years back they didn't just take one person's temperature and call that normal...they did thousands and at different times of the day to come up with 98.6.

 

The recommended procedure is to fill at same station, same pump, (if you are super anal--same time of day) allow 3 click-offs and stop. Record your volume and miles, reset and take off. After doing this for several tankfuls and you will begin to see a more accurate average value develop. Want take it a step further? Also record driving conitions with each fillup...all city, mixed and mostly highway. If you group your averages under these headings you can then see the 3 different trends emerge.

 

Cheers.

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