Hmm, I don't know. In the summary for the whole car, the "Gal Gas" field says 49.8. That is not the same as the 50.1 you get by adding the tanks up. If you divide 2928 miles by 49.8 gallons, you get 58.8mpg, which is what the summary shows. Now if you divide 2928 by 50.1, you have 58.443mpg, which more or less agrees with my spreadsheet. So it is not that I have higher resolution data than the database, but that the database itself is not consistent. And looks like the problem is in the part that adds up the individual tank consumptions.

Andy