"my gas last longer when i keep my tank above the halfway mark"
So oftentimes I’ve heard people say they rather to keep their tanks above half because the gas finishes quicker once the needle goes below the halfway mark. At first this fascinated me, i thought to myself: how could this be? so i decide to dive balls deep into this issue.
what did i learn?
Evaporation of fuel does take place inside of your fuel tank and this increases more as the volume in the tank is reduced so there is some truth to the assumption that fuel is loss due to evaporation, however: could this really be the case? could evaporation really account for such a noticable disparity? there has to be some other explaination right? and the answer is yes.
You see, manufacturers have accounted for evaporation of fuel in your tank. If you were to pull out your gas tank and observe it you will notice that there is a hose connected to it, this is for the collection of vapors, in some design this hose goes back to the tank and in some cases it feeds to the injectors so any loss of fuel is most likely due to an untighted fuel cap or leaks in your system.
Tank design
Tank design plays a major role in this seeminly complicated problem. you see: your tank is not uniform in shape. Actually; it has a pretty irregular oblong shape.
lets look at photo of a typical gas tank like the one in your car.
Now lets look at the sensor. The sensor which tells you how much fuel is in the tank does not tell what volume is in the tank, rather; it tells the position of the fuel in the tank.
what does all this means?.
when u combine the fact that your tank is irregular in shape and you have a position sensor its easy to see how you get erroneous readings.
conclusion
so its not that the gas finishes faster on the second half but rather its that there is less gas in the lower half of the tank. One way to check this is to see how much it cost to bring your tank from empty to half then compared that to how much it cost from half to full.
until next time …..drive safe!