Anonymous
Anonymous asked in Cars & TransportationMaintenance & Repairs · 1 month ago

Why do I have this strange fuel consumption problem with my car?

I am now almost certain that if the fuel level in the tank of my car drops below a certain level, my fuel consumption increases drastically. Now I want you to explain the physics of this to me and tell me how it can happen?

If I fill the fuel tank of my car to the Max and start driving, the fuel consumption for the first 100 kilometres is only 6 litres. I can stop at any gas station at this level and simply refill my fuel tank (as yo know, the gas station pumps will stop feeding fuel automatically when my fuel tank is full, which means I only need 6 litres of petrol to fill it to the Max again). Then I can drive another 100 km with my car. I can do this unlimited times. Always in the first 100 kilometers my car uses only 6 liters of gasoline.

However, if I don't refill my fuel tank after this first 6-litre fuel has been consumed, and instead continue to drive my car as the fuel in the tank decreases, the car's fuel consumption will increase (it's not linear, but it will initially increase to 9.5 litres per 100 kilometres and eventually to 12.5 litres per 100 kilometres!)

I can't understand this phenomenon at all!

This large question mark has now formed in my brain: "What mechanism can explain this weird effect?"

Don't tell me which part is problematic.... at this point I can worry less about it, although that would be also appreciated.... instead, just use your imagination and please tell me how this can ever happen to me?

Update:

Thank you for all your answers…

First of all I want to make it super clear that I don’t make any mistake in my calculation of the fuel consumption.

As said in the first 100 km, my car consumes around 6 liters of gasoline (in reality 6.2 liters to be precise).

Update 2:

Thank you for your response!

I want to type more but the Yahoo does not allow it as you know. I have to only type very summarized and short on Yahoo which I can’t… As a result I have attached my full response to your answers via this picture on “imgbb.com” in here:

https://i.ibb.co/mGXJP8W/d.png

Update 3:

This question initially was asked on a German question and answer website called “gutefrage.net”. But everyone in German made a fun out of me and did not take this serious question seriously at all. They wouldn’t believe me and thought I am crazy. So then I came to Yahoo and used a translator to translate it quickly to English. If you see the original question in here has a bad English format, it is because of this. So sorry about it.

Update 4:

The original question in German with all the laughter and ridicule I got from responders in Germany can be found here:

https://www.gutefrage.net/frage/warum-habe-ich-die...

4 Answers

Relevance
  • don r
    Lv 7
    1 month ago

    Fuel gauges are not accurate. Also 1/2 a 10 gallon tank is 5 gallons, but half the remaining fuel is a little more than 2 gallons- sloshing all around and not lifting the float the same way as the first 5 gallons did.. That last 1/2 or /1/4 may not actually be the proportional volumes you expect.

    Your fuel tank is quite small if it only holds 12 liters.

    • John1 month agoReport

      Thank you for your response!
      I want to type more but the Yahoo does not allow it as you know. I have to only type very summarized and short on Yahoo which I can’t… As a result I have attached my full response to your answers via this picture on “imgbb.com” in here:
      https://i.ibb.co/mGXJP8W/d.png

  • JetDoc
    Lv 7
    1 month ago

    The "WEIRD EFFECT" is YOU! Stop trying to judge your fuel consumption by the fuel gauge. Instead, fill the tank and record the mileage reading on your odometer. Drive normally until the next time you need to fill the tank.

    Fill it and again, read the miles on your odometer. Do a bit of elementary school math to find out how many miles you drove since the last fill up, and how much fuel it took to go that far.

    Continue to record your mileage every time you fill up the tank, and eventually, you'll come up with an average miles per gallon for your car.

    • John1 month agoReport

      Thank you for your response!
      I want to type more but the Yahoo does not allow it as you know. I have to only type very summarized and short on Yahoo which I can’t… As a result I have attached my full response to your answers via this picture on “imgbb.com” in here:
      https://i.ibb.co/mGXJP8W/d.png

  • Scott
    Lv 6
    1 month ago

    The problem is with the fuel gauge or sending unit. The fuel consumption isn't going to change based on the amount of fuel in the tank.

    • John1 month agoReport

      Thank you for your response!
      I want to type more but the Yahoo does not allow it as you know. I have to only type very summarized and short on Yahoo which I can’t… As a result I have attached my full response to your answers via this picture on “imgbb.com” in here:
      https://i.ibb.co/mGXJP8W/d.png

  • L.N.
    Lv 7
    1 month ago

    This is litterally not possible unless the fuel is running out onto the ground. Your air/fuel ratio would have to be so far off to lose that much mileage that it would set the check engine light.

    • John1 month agoReport

      Thank you for your response!
      I want to type more but the Yahoo does not allow it as you know. I have to only type very summarized and short on Yahoo which I can’t… As a result I have attached my full response to your answers via this picture on “imgbb.com” in here:
      https://i.ibb.co/mGXJP8W/d.png

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