According to reliable source oh2o, large cars with Hemi engines and eight-speed automatics won’t been seen until summer at the earliest. This does not necessarily mean they will not be open for ordering before then, but actual manufacturing will not start for months after February. The Charger and 300C would likely get the combination, while Challenger would wait until its impending redesign. All would be sold as 2014 models (technically, a car made today could be labelled as a 2014).
The eight-speed automatic is expected to increase acceleration (though not as dramatically as with the V6 cars) and to substantially boost highway gas mileage; city mileage might or might not rise as well. The eight-speed has a much higher range (gap between lowest and highest gears), allowing it to provide a lower first gear while also running the engine at slower speeds on the highway, lower frictional losses, and much faster shifting and torque converter locking than the current Mercedes five-speed automatic. It is currently only used with the Pentastar V6 at Chrysler, but Rams, Grand Cherokees, and Durangos with Hemi eight-speed combinations are due soon. The eight-speed will be made by Chrysler under license, and the Chrysler version is different in many ways than the standard ZF package.