Several Ford models have been bumped down in the "green" rankings after the company admitted that some of its EPA-estimated fuel economy numbers were inflated.

Six of the American automaker's most efficient cars had overstated fuel economy figures and have subsequently fallen in the 2013 rankings from the American Council for an Energy-Efficient Economy, Edmunds.com reported. Ford has blamed "internal testing errors" and said the mistakes have been corrected.

The change took two Ford models off the ACEE's Top 12 list of green-friendly vehicles for the 2013 model year, with the 2013 Ford Fusion Hybrid and C-Max hybrid getting bumped down.

The ACEE, which is a lobbying group for environmental advocacy, has ranked the greenest cars for 17 years.

In the earlier ranking, Ford's Fusion and C-Max had tied for 12th place in the 2013 list, each taking 51 points out of a theoretically perfect score of 100.  The Acura ILX Hybrid takes 12th place with the new numbers.

The 2013 Fusion Hybrid, C-Max Energi plug-in hybrid and Lincoln MKZ hybrid fell from their "best in class" status in the midsize segment for 2013 as well.

The number redo marks the third time in two years that EPA fuel economy estimates have been wrong, according to Edmunds.

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