Best tank ever?

I may have had my best tank ever, 57.348 (calculated) This is the story. We had a warm snap 2 weeks or so ago. Temps into the 60's even. At the end of that the weather turned and it got cold and was raining so I filled up a different pump that I usually do. I also filled the tank early at 416 tank mi because I was going on a trip the next day and wanted to buy gas locally at a known lower price. I had 53.1 mpg on the computer and had been driving a new rout too and from work that had the mpg climbing during the second half of the tank. It was in the high 30's when I filled blowing and raining sideways. The pump was one of those hard ones and I had to baby every gallon in and I put just over 7 gallons in and that was it. I did not spill but I could not get more in. I would have expected about 8 gallons. So I get the "best tank" and I figured I short filled the tank and the next one would be low but it was not. Despite bad cold weather I got 53.057 mpg, and the gage was normal no early dropping from "full" as I expected. That fill was usual at my regular pump that plays nice with my car. The second fill was also short miles 348 on the tank because I was going on a longish trip and did not want to hunt for a station in Seattle where I do not know the area and prices. So is this my new best or not.

 

Here is a follow up my last tank that I drove to the last bar was a 8.955 gal fill with a calculated mpg of 45.226 mpg my second worse tank. The computer said 51.3 which seems more intuitive as there was a longish drive on the freeway and I have been driving very carefully. Am I having seeing difficulty with the bladder that is throwing off the calculated mpg from the pump. At least one of these I thought was a short fill because I was having terrible problems with the pump shut off. I will never use that pump again. Any ideas? This is not making a lot of sense to me. Maybe the only number I can trust is the lifetime average?