how to read fuel gauge accurately?

[UpOn3]

As the title says. What's the best way or time to read your fuel gauge for the best accuracy?

Mine seems to fluctuate a lot while driving and more stable after sitting. Uphill less gas, and downhill more gas. If driving on level ground, how long does it take to attain an accurate reading?

Also, why is the half tank mark off center? When the needle is a the half mark, does it mean that the tank is exactly half empty (half full), including the overfull and reserve?

I believe I have a 14.5 Gal tank, or more, but I've only been able to get 12.5 gallons in there when fueled at 1 gallon below the low fuel light trigger. Do I really have 3+ gallons remaining when the light comes on?

TIA

[ME30W]

I'm still unsure of this myself, am looking forward for an expert to chime in. I tend to get about 180 miles to the halfway mark, but only get to about 260 before I fill up about 11 gallons. I tend not to run it too low

[Cletonius]

Wait, there's a low fuel light?

[Semblance]

^ time to replace your cluster lights... ;)

[Gregs///M]

The vintage BMW's always had this problem. First start by making sure the 7mm nut behind the gauge is tight so you have the most accurate indication as possible. But that gauge still wont give you complete accuracy. You should be reading your gauge when you vehicle is on level ground, that will give you the most accurate reading.

You can also use your OBC to view gas stats. Hit range for est miles until empty or hit "10" and "1000" at the same time for a display of your fuel level in liters.

[Cletonius]

^ time to replace your cluster lights... ;)

So it would seem

[UpOn3]

So the fuel gauges are inherently unstable and there's nothing wrong with mine?

Unfortunately I have a 4 or 6 button OBC that doesn't have those functions.

[dnguyen1963]

If you take out the fuel sender unit then you can see why it is only an estimate to how much fuel is left in the tank when it is near empty. Think about a gallon of milk and how big the gas tank is. If you pour that gallon of milk into the tank, the milk level would never reach the bottom of the fuel sender. When the light turns on, I think you have roughly 1.5 gal left in the tank. Take that with a grain of salt. Most of us here, I think, fill the tank up when there is about 1/4 of a tank left. If the light in your car turns on and you think you have about 3 gal left in the tank then you should take the sender out and give it a good cleaning.