It's a small difference, but I wonder why fueleconomy.gov has two different ratings for the automatic Fit. The Base is rated at 28 MPG city and 35 highway,
while the Sport with the automatic is 27 city 33 highway. The Sport has the same ratings for the manual transmission. Edmunds.com shows the specifics
of the models, while the EPA lists one of the automatics as 'Automatic S5' (lower mpg) and 'Automatic 5-spd. I assume the S5 is the Sport.

Could it be the wheel size difference of the Sport? It could be thought with a larger diameter that would mean slightly less rpms, therefore better MPG but
I know that's not always the case. In reality there's probably hardly and difference. I prefer manual transmissions but would assume the lower (numerical)
gearing of the automatic would mean a bit quieter at highway speeds.