Ford is also offering current customers of the 2013 C-MAX Hybrid a one-time payment of $550 (purchase) or $325 (lease) to offset the fueling difference. At the same time, said Raj Nair, group vice president, global product development, during a webcast this afternoon, Ford is upgrading the 2014 C-MAX Hybrid with new transmission gearing and enhanced aerodynamics to further improve its fuel efficiency performance.

The upgrades build on powertrain software updates Ford announced last month for the 2013 C-MAX Hybrid. Changes include:

• Gearing changes that result in a more efficient transmission drive ratio;

• New hood seal, front and rear tire deflectors, A-pillar moldings and the addition of rear lift gate deflectors to improve vehicle aerodynamics; and

• New engine oil with reduced friction.

Ford expects the enhancements to the 2014 C-MAX Hybrid will improve customers’ on-road fuel economy, especially at highway speeds. Fuel economy label testing has not yet been done on the 2014 model.

2013 C-MAX and the General Label rule. In December 2012, road testing by Consumer Reports found the fuel economy on the 2013 Fusion Hybrid sedan and new C-Max Hybrid falling far short below the touted Ford (and EPA) triple 47 mpg (5.0 l/100 km) figures—i.e., 47 mpg for city, highway and combined—for both vehicles. (Earlier post.) Consumer Reports reported at that time that the two vehicles had the largest discrepancy between overall-mpg results and the estimates published by the EPA that it had seen among any current models.

Later that month, Ford responded that it standing by the ratings as determined by the current testing protocols. At that time, Nair said that “we absolutely agree with EPA that hybrids are far more variable in the test cycle compared to real world driving conditions in conventional vehicles. We are working closely with the agency to determine if any changes are needed for the industry relative to hybrid vehicle testing.” (Earlier post.)

After receiving consumer complaints, EPA acquired a 2013 Ford C-MAX hybrid, accumulated 4,000 miles to break it in, and performed fuel economy tests. Based on the results of these tests, EPA determined that the fuel economy performance of the 2013 C-MAX was significantly lower than the original label values.

In making the announcement today, Nair again emphasized that the variability of on-road fuel economy is greater for hybrids than for conventional vehicles. Relatively small differences in driver behavior and driving conditions can have a significant effect on the degree to which a hybrid’s gasoline engine is used for propulsion, which affects fuel efficiency. That may lead to future changes in testing protocols, Nair suggested.

One of the factors behind the 2013 C-MAX fuel economy issue, Nair said, was the EPA’s General Label rule. Developed in 1977, EPA label regulations allow, but do not require, vehicles with the same engine, transmission and weight class to use the same fuel economy label value data, since, historically, such vehicle families achieve nearly identical fuel economy performance. Under the rule, Nair said, the highest volume vehicle configuration is the one used to generate the fuel economy label.

Ford based the 2013 Ford C-Max label on testing of the related Ford Fusion hybrid, which has the same engine, transmission and test weight as allowed under EPA regulations—and is the higher volume configuration. It is also a sedan, and the C-MAX is a crossover-style vehicle. EPA’s evaluation found that the C-MAX’s different aerodynamic characteristics resulted in a significant difference in fuel economy from the Fusion hybrid.

For the vast majority of vehicles this approach would have yielded a more accurate label value for the car, EPA noted, agreeing that the hybrids are more sensitive to small design differences than conventional vehicles.

To date, most high-efficiency hybrids have been used in a single vehicle design and therefore do not have this issue, EPA added. The Ford hybrid family is one of two examples in the industry where advanced technology vehicles with the same engine, transmission and hybrid components are used across multiple vehicle designs. EPA regulations allow but do not require automakers to generate a label for each design in this circumstance. With the new Ford C-Max label, each vehicle design within the two high-efficiency hybrid families now has its own label.

Ford is standing by the original 47 mpg labeling for the Fusion Hybrid.

As an interesting side-note, the two plug-in hybrids—the C-MAX Energi and the Fusion Energi—were also labeled under the General Rule, Nair said. But in this case, the C-MAX Energi is the higher-volume configuration, and so became the basis for the label for the Fusion Energi. If tested and labeled separately, the Fusion Energi might turn in higher fuel economy numbers, Nair said.

Looking forward, EPA expects to see greater use of common high efficiency systems across multiple vehicles by manufacturers in order to improve quality and reduce manufacturing costs. EPA says it will be working with consumer advocates, environmental organizations and auto manufacturers, to propose revised fuel economy labeling regulations to ensure that consumers are consistently given the accurate fuel economy information.