2002 Honda Civic with odd gas mileage

I have a puzzle for everyone out there- I own a 2002 Honda Civic. Great car, never had trouble with it. Currently has 88,000 miles on it. All maintenance is done on time, etc etc.



Here’s my puzzle.



In 2009 we moved across the country. I drove the civic. I kept track of my gas mileage the entire trip to see how I was doing. I’d write down miles drive, gallons put in. Typically I can go about 330-370 miles on a tank of gas (and my gas tank is rated to hold 13 gallons, says the manual). We’d usually stop to fill up once a day.



A couple times along the trip, the pump put OVER the capacity of my tank in the car- as much as 14 gallons. I would get OK gas mileage from these fill ups. A few other times, I would seriously drive 350 miles and put 4-6 gallons in my car. Giving my car a gas mileage of ~67 mpg.



Any thoughts on what is going on here?? The overfills and super duper mpg did not always coincide with each other- I didn’t get awesome gas mileage after overfilling. These were just random events.



Since this trip, every once in awhile, I still have a trip to the gas station where I “overfill”.



Thanks for any thoughts/help!!

It seems as though you have been hitting some gas stations that have poorly calibrated pumps. This is the only conceivable way either of these cases can occur. My car has a 14 gallon tank and usually takes about 11 gallons per fill-up from an eighth of a tank. If it ever did anything else, I would suspect the calibration of the pump. At least in some of the cases, the pump was apparently grossly inaccurate in your favor…