I have a '03 SVT Focus (stock). I have kept track of the mileage since it was new & average 28 mpg. Best single tank full was 36 mpg. The best part is I live close enough to work to walk and only have to fill up about every 4 weeks.
I had a 1992 Dakota 4cyl that I got 35mpg with in a tank full that was all highway.
Years ago a motorcycle magazine did an acticle on mpg for bikes. A leader road at a normal rate and the other bikes had to stay close enough to know where he went. They could back off going up hills, cost down, draft, over inflate the tire etc. Then at the end of the trip they figured who had gotten the best mpg. How about an article with cars!