Yep "Plum Crazy" with 8sp, and 485hp 475tq it is beyond a hoot to drive. Then again it does have twice the displacement of a Crossfire, so it should giddy up and go. I get a kick out of the young people at work asking how big the engine is even though there is a "392 HEMI" on both sides of the SHAKER. Then I ask how big their engine is, (typically 1.x liters) I say 6.4, like 4 of yours!
Gas mileage sucks around town, but no worse than my 5.7 Charger was, and highway is pretty good. My best on a nice cool day taking it easy was 29.5 over 200+ miles, but realistically 27ish is to be expected.