Welcome to Fuelly!
Looking at your log-
Smart Car Fuel-up Log | Fuelly
Your first odometer was 47,009 and the second fillup was ~57,000 a difference of over 10k miles and that would equate to something around 1087 MPG!
I'm going to assume you meant to type 57,009 as your first entry? If so, simply edit that fillup, make the correction and data will populate automatically for you.
__________________