Most of the vehicles mentioned in this thread are penalty boxes in one way or another. A Buick Park Avenue, or a Lincoln Town Car, or a Mercedes S-class would all certainly be more highway friendly. But lower MPG, higher maintenance cost, and likely higher upfront cost for a good example put these cars out of the criteria outlined in the title of this thread: "a commuter car that is fuel efficient, reliable, and low priced."
I really liked the Fit. Space, fuel efficiency, and go-cart like handling are its strong points. But I'm 30, and I understand that a more "mature" driver wouldn't care much for good handling and would prefer a plush ride instead.