The Fit has 117 HP and 100 - 105 lb-ft of torque. Not overwhelming but much more than a car that size with a 1.5 liter engine would have dreamed of 20 years ago.
A Fit has been my daily commuter for 10 years. I don't have any trouble with freeway driving, including merging, for two reasons: I bought the Sport model which has a manual mode and paddle shifters in its auto transmission, and I don't mind revving the engine into the powerband which is at a much higher rev range than most Americans are used to.
American drivers, by and large, just aren't comfortable with engines running at 5 - 6K RPM to deliver the goods.
Get it with the manual transmission or with the manual-mode AT, drive it like it should be, and it'll do alright even if you won't win any races.