How Many Gallons Are In Your Tank?

OK so all the MPG threads and it really comes down to how you drive and what your setup is. even having the exact same setup can still deliver different results based on the driver's attitude and the terrain he/she drives on.

This is not the issue of this post entirely however. We will need MPGs to help us figure out our data but here we are more focused on how many Gallons we are going to have left in our tank depending on where the needle is on our gauge.

The data below is some of what i have collected. Check it out, but read on because you will come back to it.








When trying to calculate milles between 1/4 tanks and how many gallons are in those quarter tanks you have to take a few things into consideration.

First, are you doing the math right? not saying anyone is slow here but you need to take your avg mpg and divide it into the miles for each individual 1/4 tank. you cannot just use the number of gallons it takes to fill up and divide by 4

You can do it by just waiting till you get to each 1/4 of a tank, fill up, and then check all the numbers but you have to be near a station EXACTLY when you hit that mark. you only have to be over 10 miles to be off a 1/2 to 3/4 of a gallon. You also need to do it a lot and compare your numbers to see if something was not done right. which brings me to my next point.

You have to collect the data and RECORD it, not just remember it, because you will need highs, lows, and averages to find legitimate answers.

Everything must be done the same. This is a hard one because we dont always drive our vehicles to the same places every day and in the same way (high rpms/low rpms)
I am lucky in this regard because i drive the same 40 miles through base to work everyday and i dont really go any where after work however as shown above, sometimes i did and i annotated it.

This is important because every 1/4 of your tank must be getting the same mpg.

Example:

If all of your 1/4 tanks individually gave you 18 mpgs but one of the 1/4 tanks was your worst and gave you 15 mpgs then you have flawed your data. because if you average out that WHOLE tank you may come out with a 17.5 mpg avg and be using that number to divide into your crappy 1/4 tank miles which will give you the wrong amount of gals. You will be able to get in the "ballpark" information if you have many tanks to pull data from and use highs lows and averages. but if you are using only a few tanks you could be off a little.

Another thing to consider is everyone's Elight comes on at a different time. its not too far off but it is a little i've noticed. this will only affect the bottom 1/4 tank #s. I like to use the E-light as the end of my bottom 1/4 for obvious reasons. when the E-light comes on you know you need to get gas and it is at that point that you want to know how far you can go.

Lastly, your fill up procedures must be the same EVERY time and you MUST try to get to a station, (preferably the same station since some pumps kick off differently) as soon as the Elight comes on! (or when the needle is firmly on E if that is the method you are using)

Now for the actual numbers. i have about 4 more tanks to add to the above shown data but was lazy with making a new data picture. sorry.

but here is how it goes..

17 gallons give or take .2 gallons is what it has been for me when getting to the station only a couple miles from when the E light came on.

17 Gals is what it takes MY tank to fill up after my E light comes on. remember this will only make our bottom 1/4 tank numbers different.

I use the highest miles per 1/4 tank which are highlighted BLUE and the lowest highlighted in RED and the Averages highlighted in YELLOW. this will give us consistent mpg throughout the individual 1/4 tanks.

My Average, High and Low #'s are as follows:

Highest possible- 339 miles to E-light/17 Gallons/19.94 MPGs
5.51
4.11
4.31
3.06
(add these numbers to check our math and you get 17 Gallons which allows us to know we did it right)

Lowest possible- 261 miles to the E-light/17 Gallons/15.35 MPGs
5.27
3.97
4.42
3.22
(Add these numbers and you get 16.9 Gallons which is close enough for me)

Old Average possible- 307.14 miles/17 Gallons/18.15 MPGs
5.37
3.95
4.39
3.04
(Add these numbers and you get 16.8 which is still pretty close and good enough for me-we ARE working with average miles, Average MPGs and average individual 1/4 tank miles)

New Averages since last update: 306.33 Miles/17 Gallons/18.01 MPGs
5.47
4.06
4.38
3.08
(Added up and you get 16.76 still pretty close. again these are averages so a .25 Margin of error isnt too bad)


Here are the numbers stacked side by side.

High----Old Average----New Average--------- Low------Margin of error
5.51---------5.37 ------------5.47--------------5.27----------.34 (due to difference in fuel ups most likely)
4.11---------3.95 ------------4.06--------------3.97----------.14
4.31---------4.39 ------------4.38--------------4.39----------.08
3.06---------3.04 ------------3.08--------------3.04----------.02

I feel like this is pretty accurate data considering i calculated it 3 different ways and the margins of error are pretty damn good if you ask me. the top 1/4 tank with .3 margin of error and 18mpgs is only a difference of 6 miles.

Soooo in the end you can be sure that your tanks are as follows:

Full to 3/4 ---= 5.4
3/4 to 1/2--- = 4.0
1/2 to 1/4--- = 4.4
1/4 to E-light = 3.0

For a Grand total of 17 Gals leaving you approximately 4 Gallons after thef uel light Remember that depending on when your E-light comes on you may have more or less in the bottom 1/4 tank than others and you also will end up with more or less miles after the E-light. some people may be 3.5 gallons or 3.2 after the E-light and some may be 4 it just depends. you'll know when you fill up after the E-light and it takes you 17.5 or 16.5 gallons

Miles per gallon only helps to find the gallon capacity of each 1/4 tank. these 1/4 tank numbers should be closely the same for all of us if we gather and use our data appropriately (regardless of our different MPGs).


Hope this helps some people out. there is numerous MPG threads but none with actual data charted and plenty of it. As I said before most of us can't even do this data collection because our day to day driving varies depending on where we go and whether there is heavy traffic or not. I was lucky enough to have a constant daily routine and going through base at the hour i go to and from work keeps me away from any traffic at all. 30 miles of my 40 mile round-trip can be driven at 50mph on cruise control which also helps to get accurate information.

Edit: Forgot to mention an imortant note on infromation gathering. If you are really tall/short or you have your seat really close or far away from the steering wheel this can affect the point at which you "deem the needle is resting firmly" on the the individual 1/4 tank mark. this can make your 1/4 tank data be off just a bit from mine. I'm about 5ft 10 inches, my seat is about midway to the steering wheel and my sest back is not laid way back but in a normal upright position. I make a conscious effort to make sure i am looking at the gauge in the same manner everytime i "deem the needle is resting firmly" on an individual 1/4 tank mark.

 

don't forget that you have to also take into account elevation, humidity, ambient air temps, etc...tons of variables to consider...

but overall like you mentioned in your post, comes down to what type of setup you have and your driving ability (habits)...

I have a similar routine to you...drive from home to work, work to school (UNLV), school back to home...may take alternative routes depending on if I have errands to run, get food, hang out at friends house, etc...

 

yes those environmental variables will affect MPGs but none of it will affect how many gallons you have left in your tank depending on where the needle sets on your gauge.

 

^very true...with the tank being 21.1 gallons when its completely full that means for every 1/4 tank there is 5.275 gallons...

 

The wording is important... we went through this in the other thread, too.

21 gallon tank means every quarter tank is 5.25 gallons.
However, the GAUGE lines are what is being shown in gj's graphs and charts above...

The gauge lines do not represent the actual amount of fuel in the tank... you always have MORE gas in there than what the gauge indicates.

My numbers (so far) recorded are close to gj's, but I don't make the warning light the bottom of my chart... I will continue to observe the gallons used and report changes. I have had the light come on and off and not be on when I park, and come on when I start the engine another day.

FULL: 21 gallons in tank
3/4 Line: 16.2 gallons in tank (4.8 used)
1/2 Line: 11.6 gallons in tank (9.4 used). 4.6 between 3/4 & 1/2 lines.
1/4 Line: 7.7 gallons in tank (13.3 used). 3.9 between 1/2 & 1/4 lines.
E Line: 2.5 gallons in tank (18.5 used). 5.2 between 1/4 & E lines.

gj's numbers and (my numbers):
Full to 3/4 ---= 5.5 (4.8)
3/4 to 1/2--- = 4.1 (4.6)
1/2 to 1/4--- = 4.4 (3.9)

As for miles per quarter tank, that will be all over the map because of our various mileages... I am doing the fuelly thing so you all can see my average... Right now, it is at 16.7... My range has been 15.5 to 19.2, yesterday I got 17.0.

Using miles per 1/4 tank levels at 17 mpg:

Full to 3/4 -------= 81.6 (4.8 gallons) [4.8 gal.=81.6 mi.]
3/4 to 1/2------- = 78.2 (4.6 gallons) [9.4 gal.=159.8 mi.]
1/2 to 1/4------- = 66.3 (3.9 gallons) [13.3 gal.=226.1 mi.]
1/4 to E Line----- = 88.4 (5.2 gallons) [18.5 gal.=314.5 mi.]
E Line to Empty-- = 42.5 (2.5 gallons) [21 gal.=357.0 mi.]
357 miles and 21 gallons total at 17 MPG.

 

yes I understand that...thanks dad...lol j/k

my owners manual says 21.1...that's why I put up 5.275 gallons per 1/4 tank...

exactly...

although I never have a problem with running out of gas or getting low to the point that the light comes on...cause I fill up every half a tank...and I get 210+ miles for every half tank...i can make 1/2 tank of gas last me almost 2 weeks...

 

You are lucky that gas lasts you so long! The only time I can go that long is wen I don't have work... and the last couple of years, that HAS been a problem!

I did round the 21.1... to 21.0, I understood why your 1/4 numbers were a bit elevated. I figured what is 0.1 gallon of gas? If a quart is 0.25 and a pint is 0.125, we are talking about less than 2 cups... If we fill up the tank until it is at the point of spilling out, I wonder how more gas can be in the fill line from the top of the actual tank to the entrance cap?

Thanks for the feedback... more input, more data, more fun is what a forum is about!

 

just filled up today w/ 18.8 gal

 

^i was bored today at workand figured giving you sh*t in the name of fun would brighten up my day...

yes .1 isn't a huge difference...and 2 cups...i've seen people ask the attendant can I put $4 on pump so and so...I would always think to myself I know you maybe low on $$$ but your only going to fill up 3 blocks from now...lol

everything for me is pretty much within 20-30 miles of each other...I just try to feather the throttle as much as possible that way I don't have to fill up as frequently...unless I need to get somewhere quicker and/or traffic is bugging the hell out of me...that's the only time I unleash my 4.0...I do work 4-5 days a week and have school 2 days out of the week...

I think because I grew up in hawaii and absolutely hate having to deal with traffic...I always find alternative routes (back roads) to get to my destination quicker w/less stop and go traffic...I'm pretty sure its my driving habits and the fact that I try to completely avoid stop and go traffic whether in city/highway areas...I don't like dealing with inattentive and discourteous drivers...they just piss me off...lol

back on topic...I wouldn't be surprised if the tank is closer to 23 gallons...reason I say that is i've heard stories and seen some of my friends with the 2nd gen drive 40+ miles while the gauge is sitting on E and fuel light on...maybe with how the fuel lines are run or how the tank is designed there is a gallon or two that toyota didn't advertise that way people can avoid going completely empty...

but only way to test this is have someone literally drive till the truck shuts off...but taking a vehicle that far w/fuel injected system isn't good for the injectors, fuel pump, and who knows what else...

 

Filled up from where??? When the light came on, needle at the E line, ???

(the amount would seem to indicate the E line or a ways below... 2.2 gallons to go)

gj and the rest of us are doing scentific research!

 

Well, rather than running out... just note the amount of gallons put in the tank at all fill ups... For your friends who drove so far below E, how many gallons did it take to fill the truck?

I would bet none of us puts in more than 21 gallons if we are still running when we drive to the pump... The most I think I put in was like 19.5 once, and I was sweating that I was going to run out! Heck, I still had 1.5 gallons (25.5 miles) to go before running out!

 

yes and if you tried you can put in about 2.5 gallons after the click if you "top" it off so i can see 23 if you are doing that. that is the next experiment i will be doing. I will Be seeing how many gallons i can get into the top gallon of the tank

 

yeah i was below e line

 

unless you run completely out of gas, there is not a way to really know how much your tank holds.

I know my lite turns on when I have about 16.5 gallons used. but I've driven it to where I needed 20.5 to fill her up and the gauge was as low as it can go.

they give you around a 4 gallon reserve. or at least they did for me.

same thing with every car/bike I've ever had. always gave enough so you won't get stranded

 

if you read your owners manual it clearly states 21.1...

its funny you say that's as low as you go cause your contradicting your 1st statement that you have above...lol

there isn't a 4 gallon reserve...if you were to fill up your tank let the gas settle and then top the tank off...a lot of us feel that it will only be 1-2 gallons more...that mean's our tank w/piping will hold only about 23 gallons in total...

if there was a 4 gallon reserve tank the truck would have 25 gallons of fuel in total and with my MPG average I would be seeing 500 miles for every tank...I get about 400 miles give or take a few miles per tank...the only time I saw 500+ miles on 1 tank is when driving back from Lake Tahoe to Las Vegas...majority of the time going down hill at 70 MPH...

lol now that's another funny statement...they build the gas tanks and fuel lines for efficiency...yes they may give you a gallon or 2 extra cause of how the fuel lines are ran and the ability to top off the tank completely...

I have had many trucks and street bikes in my day...I know for a fact that my '08 Yamaha R6 had a 4.6 gallon fuel tank (max capacity)...I don't see how you get an extra 4 gallons in there with such a compact fuel pump, fuel lines are a lot smaller when compared to any car/truck and aren't as long...

just a little FYI...its easier to quote people and post your statement under it...that way its easier for others to read...

 

I still think the point when the light comes on is not an exact thing, but should be noted!

I am going with this chart, as a base to compare... ignore the miles traveled part, unless you get close to 17 mpg, as I do in most daily driving. The important part is the gallons for each quarter tank and the last 1/4 to E line.

Several fill ups when your gauge is RIGHT ON the E line will tell us if that seems to be pretty standard. No danger of running out on the E line, still (at least) 2.5 gallons in the tank then.

Miles (at 17 mpg) and Gallons per section of gauge reading:
Full to 3/4 -------= 81.6 (4.8 gallons) [4.8 gal.=81.6 mi.]
3/4 to 1/2------- = 78.2 (4.6 gallons) [9.4 gal.=159.8 mi.]
1/2 to 1/4------- = 66.3 (3.9 gallons) [13.3 gal.=226.1 mi.]
1/4 to E Line----- = 88.4 (5.2 gallons) [18.5 gal.=314.5 mi.]
E Line to Empty-- = 42.5 (2.5 gallons) [21 gal.=357.0 mi.]
357 miles and 21 gallons total at 17 MPG.

 

Just have to remember that unless you do that to multiple tanks you my be wrong on one of the 1/4 tanks. if you got crappy mileage on one of the quarter tanks then the average you are using will be throwing them off because you are not using the correct MPG to divide into your gallons of that specific crappy 1/4 tank. Ive done this and have seen that it can throw your calculations off to be more or less than it should be. YOU HAVE TO HAVE CONSISTENT MPG THROUGHOUT THE WHOLE TANK, PERIOD.

I Think i have nailed it pretty good since i have done this over ten times and used all the "best 1/4 tanks" and all the "worst 1/4 tanks" so that i would have a consistent MPG throughout the whole tank. Otherwise you are using a whole tank of fuel and having to "feel" like or "assume" the last tank was pretty consistent on MPGs throughout the whole tank.

Odds are no one has a full tank of gas that is consistently 17, 18, or any other number of MPGs throughout the whole thing. this is why some people's results will be off a bit.

Through using the "best and worst 1/4 tanks" i created the most consistent MPG possible in one tank other than setting it on cruise control for 300 miles I feel that short of setting it on cruise and taking off, you will have a hard time matching my numbers for accuracy. (when I travel home in november i am going to try this to ensure the most accurate information, but it would have to be at night for no traffic)

The only tank that will be different for us is the last 1/4 tank depending on when your e-light comes on or whether you are not using the light and just the e mark. Also the1st 1/4 tank can be more or less depending on your fueling procedures and whether you "top" it off or just go to the click.

 

Yes, your figures are awesome and detailed... I like them a lot... They are perfect for your truck... My tank sample was from consistant driving conditions... ie. I was satisfied that my average was indeed 17 mpg for the entire tank... and I have noted the gallons on previous fill ups, as well.

A better way to gauge the gauge accuracy is to fill up at each marker level and note the gallons and miles traveled... but most important are the gallons.

By asking everyone to report how many gallons they use to TOP OFF (FILL UP) their tank when the gauge is over the E LINE (or other points of reference, like right when the light comes on, or over the 1/4 tank line, etc.) we can see a broader sampling of Tacoma Gauge readings.

It is likely they are nearly the same... Yours and mine were off only a about 1/2 gallon at each level.

 

However you would have to be RIGHT AT a station when your needle was firmly on your mark to be very accurate and you would also want to do this a few times for each 1/4 of the tank to be sure of your findings. but yes this would be a great way to do it as well. i just dont know how many times i or others would conveniently end up at a station every time we were at a specific 1/4 tank mark. it only takes 10 miles approximately to be off .5 gallons.

I think we are pretty good, like you said we are only .5 gallons off. but i really feel your numbers would come even closer to mine if you were able to take your "best plausible" tank and "worst plausible" tank and crunch the numbers. I did it both ways and noticed that i could be off anywhere from .3-.5 gallons on any given 1/4 tank. You'll just never have a full tank that gets a consistent MPG throughout. Using best and worst scenarios helps to avoid this problem.