With the introduction of a new eight-speed automatic transmission in V-6 models, the Charger becomes considerably more fuel-efficient for 2012.
EPA ratings for rear-wheel-drive models with the V-6 come in at 19 mpg city, 31 highway--very respectable for a large, performance-oriented sedan. And even with all-wheel drive, the V-6 lands at 18/27.
Hemi V-8-powered R/T models include Fuel Saver Technology (cylinder deactivation), and do quite well considering their 370-hp output; they're at 16/25, with AWD models down to 15/23. And if you're getting an SRT8, you're definitely not interested in gas mileage--that model gets 14/23.