MPG calculations
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Junior User
Joined: Jan 2007
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MPG calculations
Hey guys and gals,
I recently ran a full tank of gas to see what my true MPG would be start to finish. The computer said an average of 13.9mpg (that is all city driving with the longest trip being 7 miles at a time). When I filled up, I calculated manually. I got 16.4. Would I be correct in assuming that my manual calculation would be the more accurate one?
Thanks.
I recently ran a full tank of gas to see what my true MPG would be start to finish. The computer said an average of 13.9mpg (that is all city driving with the longest trip being 7 miles at a time). When I filled up, I calculated manually. I got 16.4. Would I be correct in assuming that my manual calculation would be the more accurate one?
Thanks.
Logistics Pro
Joined: Jul 2003
Posts: 3,595
Likes: 52
From: Lawton, Oklahoma
Certainly. The trip computer is an averaging device which gives a running average over a long period of time and has no idea how much fuel you added except for the approximate values it gets from the fuel sender. You know the exact amounts and exact mileage. Of course your estimate is only accurate over several tanks since the amount you top off with will vary. So your one time calculation is also not accurate. Your trip computer will be more accurate if you reset it once every couple months, rather than let it run all year long. Weather changes will make the long term estimate very inaccurate.
Posting Guru
Joined: Feb 2001
Posts: 1,514
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From: Maple Grove, PA
Originally Posted by HomerWinzlow
Certainly. The trip computer is an averaging device which gives a running average over a long period of time and has no idea how much fuel you added except for the approximate values it gets from the fuel sender. You know the exact amounts and exact mileage. Of course your estimate is only accurate over several tanks since the amount you top off with will vary. So your one time calculation is also not accurate. Your trip computer will be more accurate if you reset it once every couple months, rather than let it run all year long. Weather changes will make the long term estimate very inaccurate.
well, if he hit his trip....ran the tank down then filled it back up that would give correct mpg....or didn't he do that...maybe i'm reading something wrong..
Logistics Pro
Joined: Jul 2003
Posts: 3,595
Likes: 52
From: Lawton, Oklahoma
No he is using a trip computer giving him an average MPG, not his trip odometer. Even if he reset his trip computer to average every single tank it would only know an approximate fuel level when he refills and an approximate amount added.
Posting Guru
Joined: May 2001
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The best way to get a truly accurate calculation is to fill at the same pump for a month and never top off, just let the pump shut itself off.
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Super Moderator
Joined: Aug 2003
Posts: 25,479
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From: Isanti, MN
Naaah...
My personal favorite are the people who insist on calculating using the fuel tank capacity instead of the actual amount refilled.
"Well, since I went xxx miles on a 27 gallon tank..."
My personal favorite are the people who insist on calculating using the fuel tank capacity instead of the actual amount refilled.
"Well, since I went xxx miles on a 27 gallon tank..."
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Freshman User
Joined: Jan 2007
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If you would like to get your fuel estimator more accurate then go for a drive down the highway about 65mph and set the cruise, go to the fuel estimator info and hit reset, run that way for about 5 miles or so and that will make your gauge more accurate. Thats what the manual says.
Post Fiend
Joined: Mar 2005
Posts: 8,542
Likes: 5
From: Louisiana
Originally Posted by Crazy001
Naaah...
My personal favorite are the people who insist on calculating using the fuel tank capacity instead of the actual amount refilled.
"Well, since I went xxx miles on a 27 gallon tank..."
My personal favorite are the people who insist on calculating using the fuel tank capacity instead of the actual amount refilled.
"Well, since I went xxx miles on a 27 gallon tank..."
"I don't know"................Well if you have a 30 gallon tank, then 300 miles is 10mpg, but you have know clue so your and idiot.
MMNC (SS)(Ret)
Joined: Mar 2004
Posts: 11,606
Likes: 149
From: SE Georgia
read your mileage, fill up with that same mileage, drive, refill the tank, record your mileage and fuel it took to fill
take the 2nd mileage and subtract the 1st. then divide that result by the amount of fuel you put in the 2nd time.
= miles per gallon
sorry, it is obvious, but I felt it needed to be said. this is accurate for 1 tank only. doing this every tank and averaging them will give you an average MPG that is more accurate.
your trip computer is ballpark. not bad, but not good either. it's more of a dummy indicator to tell you how hard you're driving the truck.
take the 2nd mileage and subtract the 1st. then divide that result by the amount of fuel you put in the 2nd time.
= miles per gallon
sorry, it is obvious, but I felt it needed to be said. this is accurate for 1 tank only. doing this every tank and averaging them will give you an average MPG that is more accurate.
your trip computer is ballpark. not bad, but not good either. it's more of a dummy indicator to tell you how hard you're driving the truck.
Posting Guru
Joined: Feb 2001
Posts: 1,514
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From: Maple Grove, PA
Originally Posted by MBBFord
I love when people say "I get 300 miles to a tank, someone says me too, some one says, yeah, I only get 200" Ask all of them what size tank they have
"I don't know"................Well if you have a 30 gallon tank, then 300 miles is 10mpg, but you have know clue so your and idiot.
"I don't know"................Well if you have a 30 gallon tank, then 300 miles is 10mpg, but you have know clue so your and idiot.
Senior User
Joined: Mar 2004
Posts: 116
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From: Long Island
So, now to open a can of worms...
I'm averaging a bit over 17 mpg doing manual calculations with my 5.4L 3.73. It's mostly highway miles though.
What are you fine gentlemen averaging with your 4.6s/5.4s?
What are you fine gentlemen averaging with your 4.6s/5.4s?