Fuel Gauge normal?
 

I have owned my Volvo for about 3 weeks now and I have filled it up 3 times(once each week) each time I filled the car up I noticed something. I have had to fill the car up when the fuel gauge was on red(I don't like doing this but these past few weeks were event filled(to say the least) )

Each time I filled the car up I expected that the I would be putting at least 14 gal in the car(car has a 15 gal tank) to fill it up and each time I have only had to put in 10 or 11 gal depending if the gauge was at the top of the red or in the middle of the red. This means 4 or 5 gals were still in the tank even though the gauge was in the red zone.

Is this normal? Is there a "hidden amount" in the tank so that when you are in the red you have a few gallons left or is this a sign the gauge sending unit is taking a dump? When the car is off with the key out of the ignition, the gauge rests several millimeters below the bottom of the red(empty) part of the gauge. right after I turn the ignition on to ether start it or use the radio, the gauge will move up to show fuel level. The gauge goes to full when filled up full and works its way down to the red(empty) section as the gas in the tank decreases. Which it does in every car
Is this normal or a sign I need to replace the sending unit?

Thanks

Year and model?

Well, may not be perfect but I'd not worry too much... Gas gauges are rarely perfect--sending units are expensive.