Update...
Filled up this morning. I got about 280 miles, with the light on for a good 30.
I averaged 28.7 MPG on 87 octane according to Gas Cubby, compared to the previous tank at 30.9 on 93 octane.
Just to mix things up, I pumped 90 octane today, at $3.71 a gallon. Shell premium was now $3.89. Thanks Isaac.

 

I have always got better mpg with premium. My 08 Fit was a 5 speed manual sport which got 35 winter and 40 summer for the first 2 years but the last winter really brought my mpg down. I averaged 36 mpg or so lifetime and 1 tank best of 47. My Civic I am getting the same mpg and is a automatic and 44 mpg best 1 tank. I wish I had your gas prices, it is 4.25 regular and 4.49 premium. In the long run it costs the same but with a better running engine. I found this site to see what other people are averaging and I am getting and got a lot better then most. Browse On-the-Road Fuel Economy Data

 

28.4 MPG with Shell 89 octane, and that included 100 or so miles of highway driving for a total of 274 miles before the light. Not good. Switched back to 93. Pumped 9.63 gallons yesterday.