The 2013 Dodge Challenger is first and foremost a brash, attention-getting muscle car. So it's not all that surprising that the Challenger doesn't put any priority on gas mileage.
V-6 models are the best compromise in the lineup for those who still want to mind their gallons, their CO2, or their fuel budget. They manage an EPA-estimated 18 mpg city and 27 mpg highway.
If you opt for one of the HEMI V-8 models, don't expect them to fare very well: The Challenger R/T scores 16/25 mpg, while the manual pulls that down to 15/23 mpg. It's an even more dismal 14/23 mpg for the Challenger SRT8, but on the bright side, kick your right foot back to the floorboards and it'll probably put that blissful smile back on your face.