DETROIT -- Ford Motor has lowered fuel economy ratings for six of its vehicles, mostly hybrids, and will reimburse about 215,000 customers after the automaker applied test data incorrectly.

This is the second time in the past year Ford has had to lower mileage figures on some models, a setback to its reputation as a leader in fuel economy.

Affected are most 2014 Ford Fiestas as well as 2013-14 hybrid models of the Fusion, Lincoln MKZ and C-Max, and plug-in hybrids Fusion and C-Max Energi. Most see a drop of 1 to 5 mpg. The larger and heavier MKZ has the biggest drop: from 45 to 38 mpg in combined city and highway driving.

The Environmental Protection Agency has given Ford 15 days to correct its labels. Ford has told dealers that new fuel economy labels will be available in approximately six days and that dealers may continue selling the vehicles until the new labels are received.

About 200,000 customers are in the U.S. with 13,000 in Canada and 2,000 in markets where vehicles use U.S. testing results, Raj Nair, Ford head of global product development, said in a call Thursday with reporters.

They will receive "goodwill payments" ranging from $125 to $1,050 for the estimated cost of the difference between the previous and revised fuel economy labels. The amount varied by vehicle, miles driven and whether it was bought or leased.

Nair would not provide figures on the cost to the company, but said the amount will not have an impact on overall financial guidance.

Ford first found an anomaly in testing last October, but did not know if the issue was with the test or the vehicle, Nair said. Ford confirmed the problem in March and notified the EPA.

The error was in a portion of the testing known as "Total Road Load Horsepower" where a vehicle-specific resistance level is figured into the dynamometer testing. The load figure is determined using engineering models but is validated on the track in "coastdown testing" to measure the forces on the car as it rolls down a slope.

It was in the coasting test of the Fusion hybrid that Ford found the load numbers it was using did not match real-world results.

The problem was narrowed to wind tunnel testing after Ford changed its process. Nair said all new figures were verified in tests. The automaker will also enhance validation tests for future vehicles to make sure the error never happens again.

"This is our error. When we see an issue, we address it," Nair said. No one has been disciplined for the error, and Nair said ultimate responsibility rests with him as head of product development.

"Ford is absolutely committed to delivering top fuel economy and accurate information," CEO Alan Mulally said in a statement. "We apologize to our customers and will provide goodwill payments to affected owners. We also are taking steps to improve our processes and prevent issues like this from happening again."

No other label adjustments are planned.