When I fill up my almost-empty car (20 year old, diesel engine), if I pump 50€ worth of gas, the needle goes up to 55 or 60%, tops. But to get a full tank, I only need to pump another 15€.
Why is it so non-linear? Is it just old and out of whack? Is there a design choice in there? What am I not getting?
If you google pictures of a replacement gas tank for your car’s make and model, the shape of it might explain something. Might also be a failing fuel level sensor.