The best my 64 Barracuda got was high 20's mpg, 273 HP with Thermo-Quad, 4 speed, 276 gears, cruising steady on the highway. I got into the low 30's with a 2 barrel HP 170 in the same car, same setup.
My 09 Challenger R/T 6 speed will get 28 mpg and the Wife's 12 Charger R/T Auto will get low 30's. Both have 5.7 Hemis. Overdrive is the key, along with the dropping of cylinders on the Charger.
