Had less than half a tank of gas last night, filled it up, started my '09 XF and the gauge still showed less than half. Got home, shut the car off, restarted it - no change. Shut it off, took off the gas cap, reinstalled, restarted car - still no change.

Any thoughts?? My wife thinks it because the car didn't like the gas I put in it FYI, it was Shell 91.

 

Shell makes the "best" fuel in North America. Well, anyway, it is a top tier gas so isn't to blame. Your electrics are likely faulty. Either the sender in the tank needs replacing (most likely) or possibly a software issue in the instrumentation. Either way it is warranty and a dealer problem.

 

Finally got an appointment with my local Jag dealer, five days away and the fuel gauge is back to normal just hours after making the appointment. So I guess the thought of going to the dealer scared the gauge straight