How Much Left in the Gas Tank?

[PrincessHotcakes]

A dispute arouse with Nagol on the way back to the apartment today whereupon his eight block gas meter (no gauge or numbers on his rented Yaris) hit the bottom eighth block and was blinking just as we started the drive. 

I of course being rational (in this case at the very very least) insisted that this was intolerable and unacceptable, whereupon he kept saying "It's 30 miles on one eighth of a tank, that's still enough to get back and for me to commute for a while yet!"  A heated exchange ensued where I screamed at him foaming at the mouth that if he ran out of gas with me in the car he would never hear the end of it till he died, finally forcing him to pull into a gas station instead of trying to make his way home.

So... as a matter of curiosity, what do people out there think is the appropriate time to refill?  I personally prefer a third, though a quarter is acceptable. 

[Selden]

I voted an eighth, because I know I don't drive a great distance on any particular day.  If I do have to take a trip, I fill up regardless of how full it is.

[Virmir]

When the needle gets all the way down to the E, and the thing says "*DING* *DING* Low fuel!"  This option is not on the poll.

This is because going to the filthy gas station is an inconvenience, and thus the period between visits must be stretched out as long as possible.

EDIT: From experience, there is enough gas in the tank to get to the train station and back and then fill up next convenient passing when it first goes on E, so I'm not being irrational here.

[Nik]

Though my brother lets it go until the low fuel light comes on, ("I can still go ten more miles!"), I fill up when it gets to half a tank. Just as a precaution in case the fuel pump needs to be cooled by the gas itself. (It was a problem in Fords at one point, if I remember correctly.)

[KaiAdin]

I have a YAris (Sedan version) and we usually fill it up when the last 8th block starts blinking.

Mind you with other cars at least when the needle is at E there's usually enough in the tank to do 15-30km more of driving, which I think corresponds to the blinking fuel gauge in the yaris!

Actually I've driven it just up to the point of exhaustion, at the point the fuel is really running out, the car gets really sluggish/ can't accelerate that much! Lucky I was in my suburb and there was a petrol station about 2 blocks away! It just managed to limp in!

EDIT: if you're careful and drive pretty much the same routes/conditions from week to week, you can actually gauge by the trip meter how empty the tank is by how far you've driven! Keeping a small log book of how much miles/km per tankful can help to gauge that!

[nagolinc]

I fail to see how my behavior is anything but COMPLETELY REASONABLE.  My car (Sentra) tells me distance-to-empty, and I usually refill when this is between 30-60 miles, which is still enough to go to and from work twice.  This way I have my choice of whether to fill up at the gas-station by my house or the one by work, either one of which can be about $0.10 cheaper. 
Admitted the blinking "low fuel" light is disturbing, but I've grown numb to such things ever since having a car where the "I am about expode" (aka check-engine) light sporadically went from of to blinking to continuously on for no discernible reason.

[Karina]

I got into the habit of filling it up between half and one-third when I owned my RX-8. Mostly because if it were around a quarter tank left or less, you could run into problems with the fuel pump not sending enough fuel to the engine in a tight turn. And that's no fun. Now I have a Miata, and I see no reason to change this habit.

[Shadow99611]

I said one eighth... But I have a big ol' 91 F-250 diesel. So I usually cap off when it hits an eighth in both tanks.

It pains me to see the bill.... Last winter diesel in Alaska hit 5 bucks per gallon... Ouuuuccchhhh.... My truck (I love it to death) does about 11 mpg. That being said, I am still a high school student, and my parents decided to use my truck for haulin' things sometimes, so I'll jump in and go "holy crap!" Because both tanks are basically bone dry.

[Nixuelle]

When the needle gets all the way down to the E, and the thing says "*DING* *DING* Low fuel!"  This option is not on the poll.

This is because going to the filthy gas station is an inconvenience, and thus the period between visits must be stretched out as long as possible.

EDIT: From experience, there is enough gas in the tank to get to the train station and back and then fill up next convenient passing when it first goes on E, so I'm not being irrational here.

Virmir, you're crazy! You're going to end up killing the fuel pump on your car.  Letting your tank drop below around 1/4 full will start to put unnecessary strain on it.  Such things are not really cheap to replace either; I had to replace two on my car because I was letting the gas tank run too low between fill-ups.

Bottom line, you should fill up your tank more often.  A 5 minute detour to the gas station (where you can even pay at the pump -- you don't have to go inside to the more dirty bit) is better than getting stranded with a dead fuel pump and having to spend $500-800 replacing it!  Slight inconvenience now, or major one down the line; simple choice by my standard.

[KaiAdin]

Virmir, you're crazy! You're going to end up killing the fuel pump on your car.  Letting your tank drop below around 1/4 full will start to put unnecessary strain on it.  Such things are not really cheap to replace either; I had to replace two on my car because I was letting the gas tank run too low between fill-ups.

Really? how would it be more of a strain on the fuel pumps? I've never had that problem with any of the cars Ive had!

[Shadow99611]

You end up burnin' out your fuel pump sucking in air at a faster rate than fuel which burns out your motor and can potentially ruin your pump. Manufactures build in a bit of a safeguard by letting a few more gallons be in the tank when it says E to prevent this from happening.
 

[KaiAdin]

Ah yea I'd worry when you get to the E stage/warning light stage, but at 1/4 full (I guess for most cars?) you still have a comfortable margin to not need to worry about needing to fill up straight away!

[Shadow99611]

I tend to like to have some sprare fuel that I like to call 'stupidity fallback'. Like if you need to go somewhere in an emergency and can't stop at the gas station.

[Nixuelle]

Really? how would it be more of a strain on the fuel pumps? I've never had that problem with any of the cars Ive had!

As Shadow99611 suggested, this becomes problematic because your pump will begin pulling air at lower fuel levels, which results in it overheating.  With a fuel tank that is 1/4th full, you might expect your car to be fine, but you must also consider that you will not always be driving on perfectly level terrain, and therefore the fuel in the tank will also not be just sitting flat.  When you live in an area with lots of hills, such as I do, inclining the car a given way will alter the distribution of fuel in the tank (it is the same as tilting a glass full of water, the water tilts with the glass).  Depending on the direction of the tilt (either to or away from the fuel pump inlet) the pump may begin to partially pull air, even with 1/4th remaining fuel.  

A good example of this occurs when I am driving up or down hills.  Again, depending on the direction of the tilt of my car while driving on such terrain,  the fuel indicator can drop down to the "E" level with 1/4th remaining fuel, or appear to be 1/2 full until the car returns to driving on a flat surface.

Hope this clears things up, Kai.

[Virmir]

Ah, that would explain why I've never heard of this problem before and why (lame) family members who constantly run their respective vehicles at near-empty because they cannot grasp the concept that filling up saves them time and money have never experienced it either... FLAT BORING HILL-LESS TERRAIN FOREVER. *twitches*