I don't know the exact ratios but if the Si auto ratios are similar to the Si manual ratios, I might consider the F22 tranny instead because whenever I'm cruising on the freeway the revs are very high (~3k @ 60mph, ~4k @ 80mph). If you plan on just using this as a daily beater and want better mileage, I would go with the F22, but for a little more pep then go with the Si.