Highly doubt the shape of the tank would matter since am looking at the number of kilometers the car says the fuel should take me not the pin position.
Full tank=700km, when i measure the number of kilometers at half tank, its abt 350-400km and the cars says so, however even when the car says i have 350km worth of fuel it will only take me for 200km.
So i used to fuel 3 times in a month full tank always, so whoen i realized this, i started refilling the tank at every half tank, which was equal to 4 refills of half a tank each, saving a full tank worth of fuel in the process. This is what did not make sense. And maybe what harrydre said would explain it..

@CLK, Interesting responses, do not just look at consumption…When filling the tank from empty to half, how much do you spend and compare this to how much you spend when filling from half to full? Answer that and also read https://autos.aol.com/article/gas-gauge/ then we talk…

@Limanika, factored that in too, hence how i came with the conclusion that i actually spend more on fuel per month if i let refilled only when the light comes on compared to refilling at every half tank.
Full tank cost in the range of 6500-7k and i will refill at half tank with 3200-3500 which makes sense, for instance i do half a tank every 6-7 days, so i can comfortably refill every Friday with half a tank making it two full tanks a month, however a full tank takes me 10 days or 11 at most, making it 3 full tanks a month.

sijui nikwambie nini, i only wanted a logical explanation to my findings/conclusions, which a few guys questioned hence the detailed revelations on how i came up with the conclusions, you are entitled to your opinion though.
I was hoping someone else had experienced something similar..

while at it. when do the car consume more fuel while stopping at traffic lights. when on Neutral or Drive.

RPM is slightly high at neutral, but at Drive the RPM slows down but the car groans in pain and vibrates as it struggles to move but brakes zimenyongwo...its on load and thus consumes more power.
So RPM is not the correct measure.

At neutral the engine has to burn certain amount of gas to keep running… it is not in gear thus has to struggle a lot more.
The RPM is direct indication of the gas you are burning – Doesn’t this shows how many times the engine is revolving per minute? The more the RPM, the more the energy used?
You are actually better of engaged in Drive as this way you reduce the wear and tear when moving the stick. If however stopping for more than one minute, you are better of shutting of the engine.

At Neutral the engine struggles to run as compared to while on load???
Only if I were a blonde nurse, but with my heavy technical background, NO please, thank you.

@McReggae why is it normally advisable to leave it on drive? Any link please? My hand is always shifting that thinh to Neutral naturally when in stops!

@Impunity, there is no notable vaporisation in my opinion. Please take note:
• Fuel tanks are located on the sheltered underside of the cars, so no much temperature rise within or in vicinity of the tank. Gasoline evaporates at 350C at atmospheric pressure.
• The fuel tank has air tight lid, so no vapour leaks out of the tank.
• The air in fuel tank is always saturated with gasoline vapour, so there is negligible vaporisation.
If you left your car with half full tank for considerable period of time, how long would it take for all the fuel to vaporise and disappear?