Another fill-up using 91 octane at a Sinclair station:
261.8 miles / 14.032 gallons = 18.66 mpg
I don't know what to think about this stat. On one hand, it's pretty good mileage for winter. But on the other hand, it's been a mild winter, and it's 91 octane! 91 octane was $3.909 a gallon. If I don't start seeing 22+ mpg with 91 octane, I'm going back to 87 octane at a Cenex station.
One possible reason for the lower-than-expected mileage would be the tire pressure on the new tires I recently purchased. I like to have my tires at 40-44 psi (max load on tire sidewall is 44 psi). The mechanic or technician might have set the tires at 35 psi, which is what the tire pressure placard on the driver's door recommends.
(5 minute break)
I just went outside and checked the tire pressure, and the tires were indeed set at 35 psi. Boy, the one time I go to a different mechanic...
Yes, the ride is a little smoother at 35 psi, but I'd rather have higher MPG and longer tire life (more even tire wear at 40-44 psi).
Caravan odometer = 178,422 miles