I have a 2010 R/T. 5.7 with a 6 speed.
if you get a 2010, you want the "STP" package. They started havingg them mid-year, mine doesn't have it and neither does my parents. I've lowered mine and have a rear view camera I put in. I bought mine on ebay and drove it home from Philadelphia. I averaged 26-28 mpg on the way back. Driving around town I get 22ish now. Just know it won't be the fastest of the mustang/camaro/challenger comparison. But its tough to compare it to those anyway. I've ran a 13.9 with mine in the quarter mile. The autos are even faster. But if you have a 392, then you're cruising and keeping up with the other competitors cars.
I've fit 5 in the car and didn't get any complaints. Also I think the 2010 and older driver side front seat does not fold forward. Kind of annoying.
Like someone else said, go to challengertalk.com. Heck you can even find a good deal on one there.