Bought my 2008 Impreza 2.5i wagon in early February. Have 1,200 miles on it. I was averaging 28.5 mpg for my 100 mile daily commute. I reset the computer this morning, changed my route (more highway), used cruise control set at 70mph, and parked my car after 48 miles later with . . . 31.8mpg! That is with the last 5 miles driven on Pennsylvania Ave (heading into DC)!
I must say I am thoroughly pleased with this, especially after trading in my 16mpg truck!