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Discussion Starter · #1 ·
I am sure this has been thought of, but I have searched the forums and haven't found anything. I have been trying lately to find an easy way to calculate fuel mileage not just at each fill-up, but regularly throughout the use of the fuel in the tank. The fuel gauge in the 8th gen civic (possibly) lends itself to easy regular calculations, as it uses a definite measure for fuel level, as opposed to a needle. Here's what I mean:

At around 75-80 miles, I lose the top bar on my gauge. Maybe a day later, I fill-up and do a calculation, and if I got 80 miles before I lost my top fuel bar, I got 40 mpg, which if my calculations are correct, the top fuel bar disappears after just about 2 gallons of fuel have been used. So, that said, if you pay close attention to your gauge, when you lose your top bar, divide your odometer reading by 2, and you get at least an approximate mpg. Has anybody found this as well, and if so, are there other "bar readings" that are close to even gallon-usage? If somebody took the time to do this, imo it would make calculating gas mileage much easier! Just food for thought.
 

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You can't get very accurate by counting the number of bars. By your calculations, the civic has a 40 gallon tank. And what if you top off more, or if you fill up on a cold day and you get more gas in the tank?

You may be able to use it to say 'oh, 5 bars, 1/4 tank, I can go another 80 miles easy' but that's about it. Do it the right way and calculate at your fill-ups.
 

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Discussion Starter · #3 · (Edited)
I am not saying that there is a certain amount of fuel per bar, I just know that the first bar equates to about 2 gallons, plus or minus. I also know that the top "half" of the fuel tank is bigger than the bottom half. I already said I wasn't looking for exact readings, just close. Just was wondering if anybody knew any approximate gallon-usage levels. Also, my recommendation to you - never top off ever, the damage it can cause your car is not worth the extra few miles you might get per tank.
 

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I am not saying that there is a certain amount of fuel per bar, I just know that the first bar equates to about 2 gallons, plus or minus. I also know that the top "half" of the fuel tank is bigger than the bottom half. I already said I wasn't looking for exact readings, just close. Just was wondering if anybody knew any approximate gallon-usage levels. Also, my recommendation to you - never top off ever, the damage it can cause your car is not worth the extra few miles you might get per tank.

I'm not so sure about the top bar alone being 2 gallons.. After many fill ups and watching those bars carefully I've found this:

The top half of the fuel gauge moves A LOT slower than the bottom half. For example.. when I fill the tank to max and 'count bars' I get like 200 miles on the first top 7 bars. But, after that the next 7 bars on the gauge I only get 120 miles out of them.. For some reason the gauge seems more sensitive when your tank gets lower. Anybody else notice this?
 

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Guys, you're crediting your fuel gauge with far more precision than it really has just because it is a fancy digital gauge and not a needle. The float in the gas tank that sends the signal of how much to indicate is the exact same system that's in cars with needle gauges. The only difference is that signal gets interpreted into a number of bars of the gas gauge by a computer instead of just going to a needle. And on most cars the needle is probably controlled by a similar computer too.

bar by bar precision to figure out your fuel burn is useless and just about impossible. If you want that sort of precision get yourself a scangauge and even that is an estimate, but at least its usually within .2 gallons. The best you can do is look at the trip meter at 1/4 1/2 3/4 and empty and compare with previous tanks just like a needle gauge.
 

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I have 3 bars left and I've put 210 miles for this tank. FML?

The first bar does move a lot slower for what ever reason then it starts dropping like candy from a pinata. BUT! As ethlar said, its the same method just we have a computer that converts what the sensor reads to digital bars.

You can usually just take the miles you got on the tank/13 (I don't remember how big our tanks are). That should provide empirical evidence on what YOU are getting per tank.
 

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Discussion Starter · #7 ·
Wow, that is shitty, I have 3 bars left, and I'm at 390. Then again, my car averages 40 mpg city, 45 mpg highway. I believe our tanks are 13.1, somebody correct me if I'm wrong.





I have 3 bars left and I've put 210 miles for this tank. FML?

The first bar does move a lot slower for what ever reason then it starts dropping like candy from a pinata. BUT! As ethlar said, its the same method just we have a computer that converts what the sensor reads to digital bars.

You can usually just take the miles you got on the tank/13 (I don't remember how big our tanks are). That should provide empirical evidence on what YOU are getting per tank.
 
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