I had a 85 cutlass in 2011 with a cammed lq9 and t56 and 3.73 rear. With that car, I've had highway trips with 27 mpg. Even trips to the dragstrip with multiple runs down the track yielded low 20s mpg. Now, I have a 5.3, 4l80e, 3.25 rear car and the gas mileage seems much lower, however I...