I have 2.8 quattro. I put 20 bux of gas into the car and had a 3/4 full tank. I drive maybe 5 total miles and the needle drops to a little over half. But when i turn the car off and use it later on in the day, the needle will go back up again SOMETIMES. I know the car is a v6 but...

 

Did you checked the battery level? It could be possible that the fuel meter won't be getting enough current supply to read the values correctly.

 

It's the sending unit in the tank. Either the resistive element needs cleaning or the small wire on the float arm broke and needs repair. Simple fix.

 

Thank you for your contributions. My battery is producing adequate charge so i think it is the sending unit.