The news yesterday was simple: Ford has lowered the gas-mileage and efficiency ratings for six of its 2013 and 2014 models.
Three are hybrids from Ford and Lincoln, two are Ford plug-in hybrids, and the last is the 2014 Ford Fiesta, newly updated, which has revised ratings for four different engine and transmission combinations.
The company will send "goodwill" checks for $125 to $1,050 to owners and lessees of the roughly 200,000 affected vehicles, to compensate them for the increased gasoline they will use based on the lower ratings.
2014 Ford C-MaxEnlarge Photo
Ford worked with the EPA to revise the ratings, it says, and the agency has signed off on the new efficiency numbers--although fines on Ford itself for the errors have not been ruled out.
Fuel-efficiency ratings on window stickers for the affected models must be corrected within 15 days.
"Our mistake" in a math model
Ford says it miscalculated the ratings due to an error in laboratory-test measurements of Total Road Load Horsepower, a resistance level on the dynamometers (rolling roads) on which new vehicles are run through the specified test cycles to calculate emissions and fuel economy.
In addition, said global product development chief Raj Nair, Ford made a further error in the way it accounted for aerodynamic drag when it modeled "virtual" wind-tunnel testing of the cars in the calculations of an engineering model.
2013 Ford C-Max Energi plug-in hybrid, Marin County, CA, Nov 2012Enlarge Photo
“This is our mistake, plain and simple," Nair said, "and we apologize."
According to Ford, the company identified the error during its internal testing and validation procedures in March, and notified the Environmental Protection Agency of its findings. Then it worked together with the EPA on retesting and development of the new, lower ratings.
No intent to mislead
"Without getting too complex, we do a physical wind tunnel test, and then use a correlation factor to enter that into the engineering model--which is then the total load horsepower test," Nair elaborated.
"The error was in the correlation factor in the model.”
There was no intent to mislead the public, Nair said, and no Ford employee has been disciplined for the errors.
2013 Lincoln MKZ Hybrid, New York City, June 2013Enlarge Photo
Unrelated to prior C-Max Hybrid reduction
Nair said these new reductions are entirely separate from the August 2013 reduction in gas-mileage ratings for the 2013 Ford C-Max Hybrid only.
That model had been launched in autumn 2012 with EPA ratings of 47 mpg for the combined, city, and highway cycles, but in August 2013, the 2013 C-Max Hybrid rating was previously reduced to 43 mpg combined (45 mpg city, 40 mpg highway).
That stemmed from Ford's retesting of the car following owner complaints that real-world gas mileage was nowhere near the rated numbers.
Ford said at the time that it had simply carried over the test results from the 2013 Fusion Hybrid to the C-Max Hybrid. That's permitted under a provision of the EPA regulations that lets automakers test only one vehicle with a specific powertrain, then use its ratings for any other vehicle in the same weight class that uses the same powertrain
Because the Fusion sedan is longer and lower than the tall, chunky C-Max hatchback, their wind resistance on the highway is likely to be quite different--a factor not taken into account when Ford used that EPA provision to assign the C-Max Hybrid its original rating.
2013 Ford Fusion Hybrid, test drive, Catskill Mountains, NY, Mar 2013Enlarge Photo
The models and their new numbers
The revisions affected not only three hybrid models, but two plug-in hybrid models as well. Those Energi models not only saw their fuel-efficiency numbers reduced, but also their electric-efficiency ratings and total electric range as well.
The affected hybrids and plug-in hybrids are: