I was a buyer that waited until the 2013's were available because of the new engine and CVT, and the promised increased fuel mileage of the new 2.5.
I've been disappointed, to say the least, with mileage in the 24's for a mix of about 75% highway driving. We took one 1200 mile trip of all highway mileage, and it delivered just over 27 mpg cruising at 70 on flat roads.
Prior to buying, my principle experience had been driving 2011 and 2012 Outbacks which were loaner cars at my local Porsche dealer. And, in exactly the same conditions, their computers showed 27-28 mpg where mine shows 24 now.
So, my assertion is that the changes Subaru made to the 2013s actually reduced fuel economy rather than improved it. Looking at fuelly.com data seems to support that.
Two reactions to likely arguments.
1. The mileage of 2013s is all low mileage vehicles, and mileage will improve after break-in. I'd love to see any study that shows that mileage improves after break-in in more than a negligible way. I've tracked mileage in every car I've owned, and have only noticed an extremely small, if any, improvement. And my Outback has shown absolutely zero improvement after 3500 miles.
2. The EPA rates the 2013s higher, and their testing must have better results than prior years. Although the EPA actually tests very few cars, and generally takes and reports data from the manufacturer. And given scant resources at the EPA, they generally only test major model changes, so it is unlikely that the 2013 Outback would have been tested.
My mileage is not terrible, but is disappointing. It's not a deal breaker for me, but I do think it important that potential buyers know that the 2013s don't deliver better fuel mileage.