They were rated to get a few mpg less than the 4.0. The reason they didn’t bring them over for the Gen 5s is bc of the Dual VVT-i 4.0 that got better mileage with more horsepower than the 4.7sV8 went away when they changed the body style.
Ironically, when they offered both the V8 was rated for better fuel mileage.