There are several ways to open the gas tank door on the 2011 G37. You can:
Turn the fuel filler cap counterclockwise to remove it. After you’ve filled your tank, replace the fuel filler cap and close the fuel door until it latches shut. Locking your vehicle with your fob or power door switch will lock the fuel door again, too.
If you can’t get your gas tank door to open, you could have a problem with the locking mechanism or another component. If you can’t get it unstuck yourself, you might want to enlist the help of a mechanic to avoid damaging the fuel door.