I was puzzled by the official EPA fuel economy ratings for the 2017 Chevy Cruze diesel sedan as being 52mpg highway for the 6 speed manual transmission and only 47mpg for the 9 speed automatic (52/37/30 and 47/37/31 for the highway/combined/city fuel economy respectively). This is all the more surprising since the axle ratio for the manual is 3.65 and for the 9 speed automatic 3.17. Perhaps someone with greater understanding of automotive engineering can help explain this.