My car has 10,800 miles on it and this issue just started. When I fill the gas tank the gas gauge needle does not indicate the tank is full. The dealer technician went with me to the gas station so I could demonstrate the problem, and he agreed there was a problem. The initial "fix" was to "replace faulty canister close valve". That did not fix the problem so the car is at the dealer for the second time to address this issue. They do not know how to fix it yet so I started looking on Google for similar issues for my vehicle type - and I found some, on this site and on a few others. Check out: http://www.hyundai-forums.com/lf-2015-sonata-i45/306826-gas-gauge-calibration-2015-sonata-ltd.html

It seems to be a known issue. Hopefully I can post something positive soon.