in 2016 the Grizzly's fuel tank was reduced a bit from previous years. It sits at 4.76 gal compared to the older Grizzly's 5.3 gallons.
that said. I get better mileage out of my 2016 grizz than i ever did with my 2009 grizzly 700. Last trip out I had a 40 mile run which was a complete mix of slow ( below 5mph ) rough gnarly trails to 40 mph open gravel and everything in between. My machine was showing only 1 of 4 bars left but took only took 2.4 gallons to fill it back up. That's proving the gauge doesn't read right. It should have showed 1/2 a tank, as that's all I used.
Keep track of your gallons used for each type of excursion, you'll soon get a feeling for how inaccurate the gauge is and whats really left in the tank when it first shows empty. I'm not saying ignore the gauge, but dont put much faith in it. I've never owned any machine that had an accurate fuel gauge. Honda's, Kawasaki's, PoPo's, and Can'd Hams, they're all way off.