2012 Fit transmission gear chart
 

Not being an engineer, its hard to tell which transmission should give the best MPG. Can you tell ?

5-Speed Manual Transmission
Gear Ratios: 1st: 3.308, 2nd: 1.870, 3rd: 1.303, 4th: 0.949, 5th: 0.727, Reverse: 3.308, Final Drive: 4.625

5-Speed Automatic Transmission
Gear Ratios: 1st: 2.996, 2nd: 1.679, 3rd: 1.067, 4th: 0.761, 5th: 0.552, Reverse: 1.957, Final Drive: 4.563

In my experience, either.

Within the group of people who drive like they care about fuel economy, either transmission is capable of delivering impressive (~40mpg) economy. Anecdotally, the MT seems to be better in and around town, with many people reporting average MPG well above what I can get with my AT. But the higher gearing on the AT delivers better constant-speed highway numbers, if you live somewhere that you will be maintaining high speeds.

So I think it depends what sort of driving you will be doing. But really, it should depend on what sort of driving you LIKE - the 5mpg you save by going one way or another is minimal impact to actual fuel consumption, and won't make you happy if you are driving a transmission type that you hate.

The italics above are important, though. If you drive like a yob, your fuel consumption won't be very good. You have to drive like a real granny to hit 40mpg.

Hope that helps :)

The manual has alot shorter gearing, on the highway the 5AT would give better fuel economy as the rpm sits alot lower cruising. The manual can get equal city milage assuming driver short shifts the gears.