I drive out of town on back roads, When you need to pass one of those double grain trailers driven by some farm kid in the fall, you'll want your car to move. A 4 cyl just say's "what?" when you put it to the wood. The 4 cyl engines are good for just buzzing around town but if you get on a steep hill at freeway speeds (70 - 80+mph), well it just ain't going to happen
See Omo's reply:
You can get Camrys in 6cyl, but not Corollas. They do make Subaru Legacys in 6cyl, but I can tell you from experience that the 4cyl has plenty of power. I have no issues merging, changing lanes or overtaking on the highway in my wife's car even though I am used to a car with a big turbo in it.