I've always had cars with power (my last two were a V6 Grand Prix and V6 Malibu, both with the largest engines possible) and was really worried about a 4 cylinder when I bought my Nox, but I wanted something AWD and easy on gas. Those other cars saved my butt more times than I wanted to think about in PA traffic (we have short on ramps and crazy drivers and having a car with power was a good way to stay out of trouble).
My Nox doesn't have the get up and go the other two did, but it has plenty to make driving in PA traffic "safe". I was merging the other day when some idiot changed lanes, and the Nox did not disappoint when I needed to get out of the way; I floored it and off it went.
The only place I have really noticed an issue is when I merge onto the turnpike at a fairly serious uphill grade. I can get the Nox up to 65 before the onramp ends, but it really labors doing it (and probably eats a lot of gas too). It's a little more difficult to 'set my speed to successfully merge' at this onramp than it was with my other cars, but it's doable.
Before I bought my Nox, I test drove one in the mountains to see how it was going to handle. I had test driven a 4 cylinder Malibu before I bought my 2009 V6 Boo, and it was terrible; it down shifted all the time and I wasn't going to buy the Nox if it did the same. The Nox did fine, even in ECO mode.
I love my Nox (this from a V6 person). I have zero regrets about buying it.