I bought a hybrid Escape late last year. I do mostly highway driving, long distance trips, so I wasn't really expecting to get stellar mileage, given that hybrids do better in city driving. Even so, and even with a bit of a lead foot, I've been averaging 35-37 mpg with highway driving. In my ICE Escape, I was getting about 24 mpg for the same trips.
And when I drove across the Everglades on the Tamiami and then down to Key West and back (rarely going above 55 mph, and with some traffic backups), I got about 43 mpg. More than 600 miles on one tank.
I'm going to be spending the summer where I will do a lot more "slow" driving, so I'll be interested to see how the car does.
But I might have to decide soon whether it's reeeeally that important to use Premium on every fill-up.