It's the median of the car averages, not the tanks. There was one car added, so the median is now the average of the middle two cars. That's why the average went up.
I still wouldn't trust those figures until there's more data.
The single tank I have used so far has been posted. I'm down to 1/8 of a tank so I will be filling up and posting tomorrow. Looks like the mileage for the 2nd tank will be around 23 mpg due to wintry conditions in Boston.
