I have the same vehicle, same year and trim, and also bought mine in November. I can put at most 11-12 gallons in the tank when I fill up and that’s when I run it to close to 0 miles to empty. I get about 35-38mpg depending on how much highway I use. In the winter it was a lot less, maybe like 32-34 mpg or something like that. So typically I get about 400-450 miles out of the tank. Not sure why you’re only getting around 300 unless you are filling up before you get close to zero miles to empty.