Your car should come with an owner manual, read that.(hint: hold the square button on lower left side of instrument cluster for few seconds when MPG is displayed)

How accurate is the values displayed for the mpg's?

I see 1 mpg to 2 mpg difference from the only valid way to estimate the real mpg (fill tank, record mileage, drive, refuel again, divide distance traveled/fuel pumped since last refuel).
Display is too optimistic.