EPA: Blame Ford, Not Us, For C-Max Hybrids Not Reaching Mileage Ratings
Following Ford’s announcement that they will revise downward their advertised fuel economy ratings for the C-Max Hybrid, the United States Environmental Protection Agency said that the discrepancy between rated and real world fuel mileage was not the agency’s fault and appeared to be placing the blame on Ford for relying on the agency’s own rules, substituting data derived from the Fusion Hybrid because it shares a drivetrain with the hybrid C-Max. The EPA’s chief automotive regulator, Christopher Grundler, said that when they tested the Toyota Prius and Hyundai Sonata hybrids this summer, “It was fall quite reassuring.”
Grundler told Automotive News “The problem here is really not how the testing is done.” Grundler appeared to have been responding to Ford’s Raj Nair, global head of product development for the Dearborn automaker, who earlier said, “This is an industry wide issue with hybrid vehicles. We’ve learned along with EPA that the regulations create some anomalies for hybrid vehicles under the general label rule.”
Grundler did say that the Agency’s rule that allows very different vehicles that share the same drivetrain and approximate weight to share an EPA mileage rating will need to be changed to avoid the potential of misleading car buyers. He didn’t give a timetable but anticipated that it would take less than a year for the EPA to change the rule.
Toyota joined the EPA in pointing the finger at Ford. “Toyota agrees with EPA that this is a not a hybrid issue, but strictly an issue of how the Ford C-Max Hybrid fuel economy values were determined. We believe the current labeling methodology established since 2006 provides appropriate fuel economy label values for customers, when automakers apply these rules with good common sense and engineering judgment.”
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I would presume that the problem is that the EPA test cycle is too short to accurately calculate the mileage of the CMAX and Fusion. Ford's system differs from Toyota. Ford's setup relies more heavily on battery-only operating modes. Longer drives will deplete more battery power, which would cause the gas engine to operate more during the later part of a given drive than at the beginnning. The EPA city test starts with a cold engine and covers 11 miles. The highway test has a hot engine and covers 10.3 miles. The other supplementary tests are similarly short. Presumably, the tests are conducted with a fresh battery. I would bet that the results would be different if the test cycles were similar to what they are now, but covered longer distances, such as 50+ miles each. A longer test should remove some of the variation that comes from the battery's varying states of charge. Toyota's system makes more use of the gas engine. That makes the results more predictable, since the EPA test is measuring gasoline usage, not total energy usage. That's not necessarily better or worse, but it does make for more accurate testing.
Ford has now adjusted its C-Max EPA numbers to 45 city, 40 highway and is sending current owners a check for $550. The C-Max' fuel economy is HIGHLY dependent on driving style. It is quite possible to reach or exceed the EPA numbers. In town the trick is to accelerate slowly & maximize regenerative braking. On the interstate the car will get about 43 MPG cruising at 69 MPH -- any faster than that and mileage drops down into the high 30s. I routinely get mileage in the mid-50s on around-town drives, this is where the car really shines.