I'm sort of shocked to see that the mpg estimate for the Challenger Hellcat is at 20 mpg on the highway. I have a 2008 300C SRT-8 with a 7.0 mated to a Magnuson TVS2300 running 11 psi of boost. Even with the older transmission and shorter gearing, I still manage between 17-18 on the highway if I drive it nice and keep my foot out of it. My dyno was 621 hp and 661 tq. I wouldn't be surprised to see that Chrysler is playing their hand close to their chest and that the real-word vehicles do better with the superior gearing compared to the older LX/LC vehicles.