Couple followups:
- The 320 mi. trip is from my place to my Mom's house, and I've made the trip probably 25 times in all types of weather. And yet the fuel mileage is always almost exactly the same. IMO I can eliminate weather from the equation.
About the only other non-PCM variable I can think of is that I somehow got an extra-full fill. This is unlikely, though, since I always use the same method when filling up.
- Other than timing, are there any other parameters that the PCM supposedly adjusts in response to octane?
