What’s Going On In My Gas Tank?

Fuel gauge

The first 1/4, 100+ miles. The second 1/4, 80 miles. The third and 4th, 50 each. (Photo credit: Wikipedia)

A mystery happens in my car. It happens daily. Slowly. Inevitably. Then faster but still inevitably.

The mystery begins when I fill the car’s fuel tank. I drop back into the driver’s seat and turn the key. The fuel gauge rockets up to F. Ahhhh, such a good feeling.

A clean car with a full tank of gas is one of life’s most satisfying experiences. That feeling of automotive completeness is so important that Abraham Maslow considered adding it to his hierarchy of needs. Sadly, Dr. Maslow passed on before he finished updating the famous pyramid with an automotive layer above the safety layer but beneath love and belonging. Not many know that on the day Maslow died his car was found in his driveway, immaculate and gassed up.

Yet, as joyful and satisfying as the full gas tank is, it is the source of mystery. It causes frustration and disappointment. The full tank is potential that will never be met.

Allow me to explain.

English: Maslow's hierarchy of needs. Resized,...

English: Maslow’s hierarchy of needs. The automotive layer was to go on top of safety. (Photo credit: Wikipedia)

Let’s suppose that I am on a road trip. I fill my tank before I leave for my destination, four hundred miles away. As I drive, I see that with a quarter of the fuel burned, I’ve covered more than one hundred miles. “Not bad”, I think, “I can do all four hundred miles without getting more gasoline.”

I drive on. My iPod shuffles up the Bruce Springsteen song “Drive All Night”. I glance at the dashboard, knowing I’m going to drive just like Bruce. I look down and see that I’ve now used half of my gas. But now I’m concerned. Where the first quarter tank got me more than a hundred miles from home, the second has moved me less than a hundred miles. But really, I’m averaging one hundred miles per quarter tank so four hundred miles should be no problem.

But there is a problem. The remaining half of a tank will get me another one hundred miles. Not two hundred, because I get one hundred from each quarter. No, I get one hundred because, well, I don’t know. I just know I need gas and I’ve only gone three hundred miles.

Every car I’ve owned has worked the same way; the miles and amounts change, but the results are the same.

If this has happened with every car I’ve owned, it must happen to other drivers. I’m sure it’s happening to you too. I wish I knew why it happens because you’re really nice and I’d like to help you understand, but I just can’t.

Don’t get me wrong. I’ve tried. I’ve spent a lot of time behind the wheel trying to puzzle this out for all of us, because that’s the kind of guy I am. I’ve just never found a logical explanation.

Maybe you’ve got this figured out.

I’m always a quarter tank short of the solution. How unsatisfying.

28 Comments on “What’s Going On In My Gas Tank?”

  1. You know how there’s a sock monster and there’s always an odd sock out; I have come to believe there exists also a gas monster! Be not afraid! If seen, I’ll apprehend him! Grin

  2. Lily says:

    I don’t know if every car has the exact (or close) results as yours (1st 1/4=100mi, last 1/2=50mi or whatever) BUT it’s a fact that the lower amount of fuel in a tank, the harder it is on the car.

    And when I say ‘fact,’ I’m referring to the Gear Heads I grew up with stating that repeatedly since the 1970s. I reckon cars might do better in general (remember when you had to pump the accelerator before cranking the ignition…not too much or it got flooded?) nowadays but a combust engine’s still burning petrol.

    I try to keep my car no less than 1/4 tank (I drive a bare minimum of over 300 miles a week just to get to my rinky dink job). Where I live, you don’t want to hike several miles before seeing somebody, let alone a filling station. We’re about 10 miles either direction from a filling station on the ranch — and those aren’t places I’d recommend stopping. I fuel up nearer to town.

  3. prostreetonline says:

    What you are seeing is the “grade” or curve in which the designer of your vehicle implemented your fuel level sender and the feedback you get on your dash gauge.

    Often times manufacturers will give you this “smoosh” reading which allows for slower reading of the gas tank when filled compared to when it’s empty. This gives drivers a sense of “bang for the buck” having just filled up their tank and barely seeing it move in the first 100 miles, only to see mpg plummet shortly thereafter.

    When you see your fuel assembly or at least pictures of it, you begin to see why the gauge is telling you that the rate of fuel consumed is faster at a different point of the gas tank compared to others.

    Hope that helped! Rock on!

    • omawarisan says:

      Wow…so they factor in my fuel consumption satisfaction as a factor in my overall car satisfaction?

      • prostreetonline says:

        Yes! Everything single thing that you interface with is something the big corporations spend thousands of dollars in focus groups and research on.

        Some practices, like the fuel level sender are so widely accepted that most people have no idea this is happening to them.

        If you think about it, when you fill up when you are most likely to reset your “trip” meter and actually pay attention to how much mileage you have traveled. When you see the first quarter tank being spent with great results, you feel great when in reality, carrying a full gas tank should NEGATIVELY affect your gas mileage as you are increasing your weight.

        You’d be surprised to what length manufacturers will go to give the consumer ( you and I ) the warm and fuzzies about any aspect of the car they built.

  4. Ahhhhh, the mysteries of the gas tank. Many is the man who was driven mad trying to figure that out.

  5. Anonymous says:

    First of all, I appreciate you taking the time for all of us to ponder this very essential matter. Having a full tank of gas plus a clean car is very special indeed! You are on to something here with the mystery gas tank. I feel it in my bones.

  6. knace says:

    I had never noticed this! Much to the irritation of my son, I’m the person who will suddenly say “Oh, Crap- the gas light’s on!- well, I’m sure we have enough to get us to….”
    “Mom! We need to get gas NOW!” Erik will glower at me until we do.

    I would be willing to bet you’ve never run out of gas, have you? You, of the clean car and full tank! =)

  7. My human development professor said, with a thinly veiled effort to hide her snark, that Maslow believed himself to be one of the very few people in all of history to have achieved self-actualization. I believe you may have inadvertently uncovered evidence that however self-actualized he may have been, he probably wasn’t very good at calculating fuel efficiency, so he drew a colorful picture instead.

    Now, Erickson? That guy could drive 400 miles without a pit-stop.

  8. Laura says:

    I think what’s happening is that your car is lying to you. It considers the last quarter-tank to be the dregs, and it doesn’t want to drive around on that. So even though you’d be able to go another hundred miles without running out of gas, your car tells you it’s empty.

  9. As soon as I leave the gas station my car is half empty…or maybe it’s because I can only afford half a tank…

  10. When I fill my tank, it stays full for a couple of days worth of commuting, then sometime during the third day, the needle is suddenly below a quarter tank and dropping fast. I’d watch it more carefully, but I kind of need to keep my eyes on the road.

  11. Blogdramedy says:

    Maybe it’s the tunes on your iPod. Maybe you need to change to some Chamber music.

  12. Debbie says:

    I’ve noticed this also. When you find the answer, please share. That said, I never let my gas tank level drop too low. Wonder if that means I’m getting better gas mileage all the time (or just fooling myself??)

  13. I have no idea, but I do know that after the gas light comes on my car will run for about another 40 miles or more in the city. I call it driving on my imagination. Love a clean car, I wouldn’t know about a full gas tank.

  14. Dan Hennessy says:

    My advice would be : NEVER fill the tank . Clean car , okay . Filling the tank is like giving the military money for hammers or toilet seats without any control of where the money went . Your car is taking you for a ride !

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