Distance to empty miles keeps getting lower every time I fill up. Why? on 2013 Hyundai Sonata

In Jan I got a 2013 sanata. First time I filled up distance to empty miles was 503. After that fill up the miles to empty started decreasing. Just filled up and it said 435 miles to empty that is a major diff to me.

Asked by for the 2013 Hyundai Sonata
It's based on YOUR driving habits/conditions.... No way the computer can know how many miles it really is going to be until the tank is empty!... Its just a best guess!!