Both mondeos I've had got slightly worse fuel economy on cruise, but the comparitive lack of effort more than made up for it.
When you get to a hill, cruise waits for the car's speed to drop below a specified % of the target speed, and then accelerates to get your speed back up. In essence every hill you come to you'll end up accelerating up it. If you drive with your foot, you may increase your speed at the bottom of the hill to power up it, or let the speed drop on the incline. Difference was at most 2-ish mpg tho.
When you get to a hill, cruise waits for the car's speed to drop below a specified % of the target speed, and then accelerates to get your speed back up. In essence every hill you come to you'll end up accelerating up it. If you drive with your foot, you may increase your speed at the bottom of the hill to power up it, or let the speed drop on the incline. Difference was at most 2-ish mpg tho.