Still, as Ford pointed out in an email to Autoblog, the Fiesta ST delivers considerably more cargo capacity at 15 cubic feet in hatchback configuration, while the 500 Abarth serves up just 9.5 cubes. What's more, the US-spec Fiesta ST will be offered as a five-door hatchback, with considerably more rear seat room for people and things.
When asked, a Ford spokesperson confirmed to Autoblog that these numbers are the result of testing done by the automaker, not the EPA itself. The 26/35/29 ratings what Ford has submitted to the EPA for certification, and if the EPA wants to re-test, it can. (This is all standard operating procedure on the path to EPA ratings.)