Damn I really can't figure out why I am getting such shit gas mileage. I never hit 40 but can get pretty close, and when I calculate real gas mileage I on average get 26 mpg, worse than my 2013 Accord Sport with the same drive. I was hoping switching to the MXM4s would help increase a bit since they were amazing on the accord, and $40 cheaper per wheel on the civic.It's definitely your tires... I've noticed this myself. I can't believe how loud they have become... but they are also the reason I'm getting 45mpg.
I'm going with a much more premium tire when I replace. I'm thinking Michelin Primacy MXM4.
I'm also planning to do my sound deadening this year, but tire noise is the hardest to remove acoustically.