3.6 Pentastar?

my wife's 19 Cherokee has 3.2L Pentastar. Our old Cherokee's w/4.0 I6 got 15(when A/C is on) to 20mpg. Her new Cherokee gets 24 to 29mpg w/AC on all the time. I liked the old 4.0, it's tough as nails. But the new Pentastar is much smoother, much quieter, more powerful.