Ford is reducing the miles per gallon in advertising for six automobile models, company officials announced on Thursday.
The company attributed the reduction to errors in its testing of 2013 and 2014 models, including its hybrid vehicles.
Ford CEO Alan Mulally said the company was voluntarily releasing the findings because "Ford is absolutely committed to delivering top fuel economy and accurate information.
The Environmental Protection Agency said Thursday the affected vehicles were Ford's 2014 Fiesta, 2013 and 2014 Fusion, C-Max and Lincoln MKZ hybrids and the 2013 and 2014 Fusion and C-Max Energi plug-in hybrids.
The agency said the Fusion hybrid went from an advertised rate of 47 miles per gallon to 42 mpg, while the C-Max hybrid was reduced from 42 mpg to 40 mpg.
The changes comes as the Obama administration is gearing up to begin implementing new regulations that will require car manufacturers to increase the average fuel economy of their auto fleets to 54.5 mpg by 2025.
The requirement is scheduled to start at 36.6 mpg in 2017.
The EPA said Thursday it was notified of the errors by Ford.
"Ford recently alerted EPA that it had identified an error affecting fuel economy values for a number of their vehicles," the agency said on its website. "Specifically, Ford discovered that it underestimated some of the real world factors, including aerodynamics and tire friction that are important inputs into fuel economy testing.
"EPA worked with Ford on an extensive re-testing program to correct the error, overseeing Ford’s fuel economy tests, and also conducted independent testing at EPA's National Vehicle Fuel and Emissions Laboratory in Ann Arbor, Michigan to confirm the results," the agency continued.
Ford Vice President of Global Product Development Raj Nair said the company accepted responsibility for the mistake and would reimburse drivers who are negatively affected by the false information.
“This is our error. When we see an issue, we address it,” Nair said in a statement. “That is why we notified EPA and lowered the fuel economy ratings for these vehicles.”