The Environmental Protection Agency is tasked with providing the data used to calculate the average fuel economy of new cars and trucks. With innovative new vehicle models hitting the market, the standard metrics the EPA uses to measure vehicle fuel efficiency are proving ill-equipped to offer accurate comparisons in some cases.

The EPA announced yesterday that it is revising estimates for the 2013 Ford C-Max Hybrid’s fuel economy to reflect consumer-reported versus estimated mileage – 47 miles per gallon for highway, city and combined driving was downgraded to 43 mpg – as well as revamping its fuel economy labeling regulations to try to keep pace with market innovation.

“Developed in 1977, EPA label regulations allow, but do not require, vehicles with the same engine, transmission and weight class to use the same fuel economy label value data, since, historically, such vehicle families achieve nearly identical fuel economy performance,” the EPA said in a statement.

“New vehicles are more sensitive to small design differences than conventional vehicles because advanced highly efficient vehicles use so little fuel,” and “EPA expects to see greater use of common high efficiency systems across multiple vehicles by manufacturers in order to improve quality and reduce manufacturing costs”.