'09 R/T 6-speed with 20s/3.92s, BP/Amaco 93 exclusively. At 2000 miles, took car on 1800-mile Lake Superior "great circle tour". Several hundred miles at 55 mph gave 28.4 mpg (and slowly climbing). Over-all mpg for the entire trip: 26.9. Around town: 22. 18-mile work commute (2/3 city, 1/3 county highway): 25. Mind you, all of this (except for the 6th-gear, straight highway stuff) is while driving for fuel economy...consisting of gear skipping, short shifting, and lots of coasting.
I work in the plant where the 3.5L V6 is produced and it is a terrific engine, but I only drive manuals so I was forced into an R/T. It didn't bother me much as I also wanted all the goodies and couldn't have gotten them with the V6 anyway. I'm very satisfied with the car overall, and the mileage in particular.