I am getting 28-31mpg in mixed driving, slightly higher in hwy.

OurGL:
I think your VUE-GL has a problem. My worst mpg was about 23 mpg in subzero weather, warming up the car to scrape windows, driving through snow and slush with no autostop or regen until the last few miles of my commutes. I would have the dealership check your car's computers, parts, tire pressure or whatever else can affect the mpg.
My tire pressure was set 7 pounds too low for a while. At the rated 35 pounds, it drives better too.
With my driving, a preHybrid VUE with a smaller engine was getting about 22 mpg, so the hybrid system certainly does help.

By the way, how do I add my mpg to the stats page. The VUE GreenLine picture button doesn't do anything when I click it.