I’m not saying there isn’t an issue, but I believe they all stay “showing full” for quite a few miles after filling up. How many miles depends on how much you put in the tank and how you drive. I stop filling when the pump auto shuts off, and mostly the gauge shows full for the next 70 - 80 miles, then drops rapidly to 3/4 full. It’s a Plus Six, slightly thirstier than a Four, so maybe 100 miles isn’t too unusual.
I zero the trip meter after filling up and start to think about refuelling after 240 miles, or thereabouts.
Fingers crossed that this may also be a “feature” on your car.
