Does the Genesis GV80 require premium gas?

The door of my gas tank says "Premium Fuel Recommended". So I use Premium Fuel, what ever the highest octane is at the pump. My salesman told me that I would get better gas mileage with the higher octane fuel. Right now I think I'm averaging 19. But would have to look at the dash to see the exact number.

I ran my Acura MDX for years on Mid-Range (89) fuel, and am doing the same on the 3.5TT GV80 Prestige. Performance seems unaffected, still peppy and smooth. Not sure if I am losing mileage, but the $0.40-$0.50 per gallon makes up for the difference.