The owners manual states that my car’s gas tank holds 10 gallons.
If I fill it up and the gas pump clunks off at 9 1/4 gallons, does that really mean that I had 3/4 of a gallon left? Or in other words, if the tank was 100 percent empty and I filled it up at the pump, would the pump shut off at 10 gallons? (Yes, I could drive the car to the station and let it run for three hours until it ran dry, but I’m trying to avoid that experiment!)
The reason I ask is that I get about 30 miles to the gallon. If I REALLY have 3/4 of a gallon left, that means I should have ABOUT 22.5 miles left. The nearest super-cheap gas station is 29.5 miles away (I live in the country, where EVERYTHING is at least 25 miles away) so I’m wondering how close I can cut it.
It certainly would be nice to know the year, make, and model of the car…
It means you have ROUGHLY 3/4 of a gallon left. Or perhhaps 1-3/4 of a gallon left. Or maybe 1/2 gallon left. And if it’s a Rolls and you’re using american gallons, that would be about 7/8 of a gallon left. Imperial gallons, you know.
Gas gages are not precision instruments. And the volume listed in the owner’s manual is a “rounded off” figure. One thing I do know is that manufacturers always leave a “buffer” after the tank says “E” to protect the fuel pump. I also know that an Imperial gallon is about 20% larger than an american gallon, so if you have a vehicle manufactured using imperial units, say a Land Rover, a Bentley, or even a Canadian car, and you’re using Imperial gallons, your figures will be different from mine.
Touche! The car is a 2007 Honda Fit, so in theory they should be measuring “American gallons”.
The gas tank is actually listed in the owner’s manual as 10.4 gallons (I was using 10 gallons for illustration purposes and because my math stinks).
The gas line thing is a good point. If you took the tank out of the car and measured its volume, I’m guessing you come close to that 10.4 gallon number, OR is it 10.4 gallons only if you fill up to the very brim of the fuel cap opening (which I don’t do). Forgot to consider that when the pump shuts off there’s usually room for another 1/2 gallon. I don’t put that in, but is it considered part of that 10.4 gallons? Whee!
That 10.4 gallons…do you know if the manufacturer factored out the volume taken up by the fuel pump and its stuff (like the float mechanism) after calculating the tank volume?
These numbers, the gas tank volume and the fuel gage, are not precision measurements. They give the oqner an idea of about how mych gas he/she has, but that’s about it.
Once, in a fit of boredom, I figured out that 100’ of 3/8 ID air hose would hold about .57 gal. There would be one helluva lot of fuel line snaked through a car to hold a half gallon of fuel.
@gleng1 Your Fit must have a fuel warning light. When that comes on fill the tank (to first click) and take down the reading. Compare this with the 10.4 gallons in the book and that’s what you have left when the light goes on. Do this twice, while also filling up AT THE SAME GAS PUMP. The average of the two will be the reserve left. Don’ use the gas gauge reading itself; it is inaccurate as others will testify, and only gives you a general idea what’s left…
Please don’t be so foolish as to run the tank dry. With today’s cars that may wreck the fuel pump and cause all sorts of other problems. If you visit Canada, the pump readings will read in liters. There are 3.8 liters in a US gallon.
Some like the thrill of trying to drive on vapors; there are other less risky thrills.
real simple how low do you feal safe trusting the fuel gauge. i would say don’t let it get below 1/4 mark on the gauge that will also keep the pump covered in fuel and keep it cool
My words of wisdom are simply not to cut it that close. First, if you live in the country, it’s going to be a major inconvenience (and possible expense) if you do run out of gas somewhere, especially on a cold winter night. Second, I’ve always heard that the fuel pump is kept cool by the gas, which extends its life. Third, if you or a loved one needs to get to the emergency room in a hurry some day, do you really want to stop for gas along the way because you can’t make it there otherwise? Whatever small amounts of time you’re saving by filling up less often don’t offset these disadvantages.
When my car gets to 1/4, that’s when I fill up at the next convenient opportunity.
As far as I know, we don’t have any gas tank manufacturers here, so I don’t know how the capacities are determined. You need to leave a little space at the top of the tank for expansion or you will get liquid gas in your canister and damage it. There is also a small amount at the bottom of the tank that the fuel pump can’t pick up, so the useable capacity may not be as great as the stated capacity.
My grandfather once told me, it costs the same to fill the top half of the tank as it does the bottom half. If you are putting 9.2 gallons in a 10.4 tank, I think I would consider that to be the useful range of my vehicle.
My car has an insane gas gauge…I’ve seen it go from “3/8” to “E” and the warning light in a couple of miles!
I learned this trick when I drove a cab (different car every day): I zero the trip odometer when I gas up, and roughly figure how many miles I’m good for (mpg of my car X number of gallons in tank). When the gauge shows 3/8 or less I start checking how many miles I’ve driven. This is a lot more reliable than the gauge.