Fuel guage question.

[Cavs]

Im pretty sure my fuel guage is screwed, as it constanlty goes from 20l into the red and up to 10l and so on and so on, but thats not what my question is about. When the needle is in the red does it go all the way to the bottom of the red block when you reach dead empty, or does it stop at the top of the block when you run out. Just a question in case I get stuck somewhere.
Thanks in advance.

[BMW 5 SERIES]

It is very possible to get this readings if you are in the move and the remaining gas is at this low levels. Depending on the surface of the road the gas level sender sent different measurements. When you reach to low on gas a orange indicator will light up under the red strip (empty) of the fuel gauge

[Cavs]

Yeah, but when the light is on will the needle go all the way to the bottom of the red strip, or stay at the top?