I have a 2014 Malibu lt 2.5 . May commute to work is very
short. I live in Phoenix and my longest drive is to see my
kids In Yuma Arizona which is about 165 miles. Rite off the
bat within 10 miles of driving I noticed my gas needle has
moved 1/4 tank. Yesterday I filled up at Costco which is 5
minutes from my house when I got off work it had already
went back past the full line. So i decided to see how much
was used so I went back to the gas station to add more
gas, while waiting i checked my fuel range which said only
309 miles which i know couldn't be rite. When I attempted
to put gas in the car it only took 0.70 gallons. And the fuel
range only went up to 317 but by the time I got home it
went to 320. Something is wrong....
Any check engine lights? Older Malibu models had issues with the electrical circuit to the fuel level sending unit. In your case I would check the gas cap (it's a good idea to replace them after several years), the tank's vent line and/or EVAP system, then the fuel sending unit/circuit. As you're not reporting any check engine lights or other symptoms you most likely have an issue with the fuel sending unit, which is part of the fuel pump assembly, but don't rush to replace it as the problem may lie in the circuit to that assembly.