Ford C-Max Hybrid owners and Consumer Reports find mileage running short

The rumblings within the auto industry over the fuel economy of the new Ford C-Max Hybrid and the related Ford Fusion Hybrid broke into the open today when Consumer Reports announced both cars had fallen far short of the mileage promised by their window stickers -- with the C-Max some 10 mpg short of its 47 mpg rating and the Fusion Hybrid off 8 mpg. Ford has said everyone's mileage will vary, but the largest tracking of mileage by C-Max owners online backs up Consumer Reports.

After the recent debacle involving Hyundai and Kia inflating mileage estimates on 900,000 cars, there's been more concern about automakers overstating their efficiencies. While the U.S. Environmental Protection Agency sets the rules for testing mileage, automakers self-certify most of the models they sell, with the EPA only sampling a small fraction as a backstop.

Consumer Reports says it tested the mileage on the C-Max and the Fusion Hybrid using a standard series of experiments it runs on all new models, including running up 2,000 miles of break-in time and using different drivers to compensate for driving styles. The result: the C-Max averaged 37 mpg, while the Fusion Hybrid hit 39 mpg. It's the largest difference between window-sticker figures and its testing that the magazine has seen. Jake Fisher, director of auto testing at Consumer Reports, says this means "most buyers won't get anything near 47 mpg in the real world."

Those results have been questioned by some, including Ford, who says some owners report getting better than 47 mpg. But there's another way to see whether the C-Max and Fusion are living up to their billing.