Since February I've been putting my gas mileage for my 2010 R/T manual into the "Your MPG" feature on fueleconomy.gov. Their database seems to be down right now, but IIRC I averaged 21 MPG for February and March with mostly-highway, non-commuting use. The best I saw in that period was about 23.5 MPG, and last summer I saw up to 25 on highway trips. I only just started commuting with the Challenger again this spring, but I don't remember seeing worse than about 16 MPG on any given tank last summer/fall. Overall I'm very pleased; my Challenger replaced a '96 Ford Thunderbird V8 and I'm getting mileage at least as good as the T-bird ever did in the last 5 years, while having nearly twice as much horsepower.