Once again, people expecting to drive a 1.5 liter car like they would drive a 3 - 5 liter engined car. It just doesn't work.
I know exactly the roads you're describing. It's part of my home turf. Drive around and through Cincinnati and into northern Kentucky more than a few times a year.
My Fit has no trouble through those roads, but I will override the auto shifter and will climb those hills in 3rd gear at 75 mph while you were probably gasping for air in 4th.