I just purchased a 2015 Altima SL. What I loved about the car was the mileage per gallon. It started out good. When I purchased the car when filled it would say I could go over 400 miles. Now when I fill the car it only says I can go 318 and it rapidly falls. My commute is 16 miles total to and from work. It just doesn't make sense to me. I've tried using Chevron mid grade as well as shell regular. When I purchased the car and asked what gas to use I was told I could use any. I previously had a 2003 Altima 3.5 and downgraded to the 2.5 to save on gas now I am disappointed. Anyone else having this issue or know what I am doing wrong?