Sept MPG by tank fillups

Fill-up date: 9/4/10
Miles traveled: 381.4
Trip Est. mpg: 50.9
Fill-up gal.: 7.9
Fill-up mpg: 48.3
Average mpg: 49.6

Fill-up date: 9/13/2010
Miles traveled: 364.6
Trip Est. mpg: 50.2
Fill-up gal.: 7.6
Fill-up mpg: 48.0
Average mpg: 49.1

Fill-up date: 9/20/2010
Miles traveled: 394.9
Trip Est. mpg: 51.4
Fill-up gal.: 8.2
Fill-up mpg: 48.2
Average mpg: 49.8

Fill-up date: 9/28/2010
Miles traveled: 389.2
Trip Est. mpg: 49.5
Fill-up gal.: 8.4
Fill-up mpg: 46.3
Average mpg: 47.9