UPDATE: Ford Revises Fuel Economy Rating for C-Max Hybrid

Ford Motor Co. has lowered the claimed fuel economy rating for its C-Max hybrid MPV to 43 mpg from 47 mpg.

The company also will distribute "goodwill" payments of $550 to current C-Max owners and $325 to customers who have leased the vehicle. The payments are to cover the estimated difference in fuel costs based on the two ratings.

Ford has revised the C-Max with new transmission gearing, lower-friction engine oil and several aerodynamic tweaks to bolster fuel economy at highway speeds.

The 2013 C-Max had been rated by the U.S. Environmental Protection Agency at 47 mpg for city, highway and combined driving. The plug-in version of the car, which carries a larger battery and can travel farther on electric power alone, has ratings of 44/41/43 mpg.

Ford says it calculated the original mileage figures by following the required EPA test method.

But the agency launched an investigation earlier this year following consumer complaints that they could not achieve the C-Max's rating. EPA says its poll of owners indicates a real-life average of 39 mpg for the car.

Analysts note that the EPA test cycle is sensitive to when and for how long hybrid powertrains operate in electric-only mode.