The 600 mi R/T was similar, and I even nudged the cruise control up to 77 - 78 mph for most of the drive. (I've also been maintaining 32F/34R tire pressure with the new, accurate gauge I bought.)

Slightly mysterious results, but pleasantly so with premium now at $2.40 in my near environs.

I've also noticed about a 1 mpg bump with my around town driving...this despite the fact that I've recently been accelerating much harder to the posted limit than I was doing the first months I owned the car. (Maybe I've adapted to how the car prefers to be diven.)

At any rate I spent in excess of $400 for this "routine" 60k maintenance (a first for me with nothing amiss with a vehicle) but feel I got some direct, however small, payback.