You should probably check out the Nissan family of sedans. I'm thinking Altima or Sentra for your basic requirements.
Nissan doesn't stuff any old automatic into these vehicles, they pick the industry's best CVTs for duty when the automatic option box is checked. The CVTs will keep your engine humming a long in its power band ALL the time and exactly when you need it. Accelerating to highway speeds is a slight bump of revs and the world's smoothest acceleration away. I'm not kidding about smoothness, Rolls Royce automatics shift less smoothly than Nissan's CVTs.
The Altima with the 4-cylinder (I assume you want this since the 6 is power house and a bit of a pig on gas compared to the 4) nets you 23/32. The 2.0 litre sentra which also uses a CVT will net you 27/34. My Dad has the 2.0S and hasn't had any issues outside of a leaky weather stripping on the passenger side; the dealership changed ALL of the weather stripping at once.
For myself, I have the 2011 Sentra SE-R Spec-V with the High-Output version of the Altima 2.5 Litre engine that makes 200hp at revs to 7100RPM all on the good old Premium Octane: http://www.fuelly.com/driver/doverosx/sentra
. If those numbers are what I can achieve with a close-ration 6-speed, imagine the 2.0L with the CVT. If you look at the graphs, the 30+mpg was achieved by turning off my engine at long intersections, my city is retarded when it comes to traffic flow.