fuel guage erratic
The reason for this is the oxygenated fuels these days corroding the electrical contacts on the fuel level sensors.
If your car is under warr or ext warr Go to the dealer. They have updated fuel level sensors in stock if not. They have to order coded to your chasis. They also modify the new ones before they install them, they removed the float
arm mechanism and put a slight bend to the arm giving the contacts and closer mating surface gotta go.