2011 Optima EX just started this today: fuel light is on, says it had 40 miles to empty. So I stopped to put fuel in ( my daughters car so I was sure it was empty ), it held 2.1 gallons and was full of fuel for 100% sure. Got back in, started the car and it’s just over 1/2 tank with 240 miles to empty. Anyone experience this issue? Things to check?