Oh it could be a LOT better but CARB & EPA got their damn fingers in it..... If my 2003 Buick LeSabre can knock down 28MPG with 192K on it why can't a midsize car do it now? If you had a custom tune done it would wake that Hemi up & better the MPG.
Back in 2005 I had a new GMC K1500 Regular cab short bed. It had the 5.3 LS in it and we did a custom tune, headers, no cats, true duals and a cold air intake. WOW did that wake it up. I had plans to put a cam in it but the tranny started getting soft at 35K. I guess shifting it at 6200 wasn't the best idea and I was WAAAYYYY past the "allowed" input torque for the 4L60E. I was going to put a 4L80E and the cam but then thought it wasn't such a good idea since the next thing would have been a turbo....