I was under the impression that the EPA took aerodynamic parameters into account in the final calculations for their dyno-based fuel economy testing/simulation. (Of course, can't find the link at the moment...) Or rather, that the automakers took it into account when providing data to the EPA based on their test procedures.
So why then would the presumably heavier as well as less aerodynamic
2009 Jetta Sportwagen with its likely higher Cd
and (slightly) more frontal area (standard roof rails) have an identical fuel consumption rating as the
Jetta sedan equipped with the same drivetrain?
I find it difficult to believe that the actual fuel consumption isn't at least 2.4% different (2.4%=1 mpg from the 41 mpg hwy rating for the TDI M-6) between these two vehicles.
Yet the cars' ratings are
identical for every powertrain variation.
I don't buy it.