Ford lowers C-Max Hybrid fuel economy rating, makes more updates for 2014

Revised fuel economy numbers point out more loopholes with EPA estimates

Published: August 15, 2013 04:30 PM

In a tacit admission that some of its hybrid models are falling far short of their advertised, official fuel economy ratings, Ford is lowering the window sticker ratings of its 2013 C-Max Hybrids and making another round of updates to boost fuel economy of 2014 models.

The 2013 C-Max was originally rated at 47 mpg in city and highway driving and 47 mpg overall. But, according to Raj Nair, vice president of global product development at Ford, the C-Max was never actually tested on the EPA driving cycle. Instead, it was assigned the same fuel economy rating as the Ford Fusion Hybrid. That Fusion uses a similar powertrain and has a similar weight (both about 3,600 lbs.), but it is otherwise a different car. The C-Max is based on the Focus platform, in a completely different vehicle class. This has been common practice among automakers and the EPA since the 1970s, and this methodology has usually been fairly accurate, he said. But it does raise questions about how the fuel economy for one model can be applied to another, and it may explain the deeper meaning of "your results may vary."

Based on new tests, including software updates to the 2013 C-Max, Ford is issuing new fuel economy estimates for the 2013 C-Max Hybrid of 45 mpg city, 40 mpg highway, and 43 mpg combined. Automakers conduct most EPA fuel economy tests themselves, with EPA spot-checking about 15 percent of them. (Read Ford to improve fuel economy of existing hybrids.)

Consumers reporting their own fuel economy on the EPA's website said they got an average of 39 mpg. When we tested the C-Max in our real-world fuel economy tests, we got 37 mpg overall. That's much closer to what consumers are reporting than the EPA's estimates, which were supplied by Ford, based on the Fusion Hybrid.

We also reported a variation between city fuel economy of 35 mpg and highway fuel economy of 38 mpg, rather than the EPA's implication that the C-Max's fuel economy doesn't vary. When we first published our results, we called Ford and the EPA to task on the inaccurate ratings and called on the EPA to update its test protocols. (Read The mpg gap: Some window stickers promise too much.)

For the 2014 model, Ford is making hardware updates to the C-Max, including a higher final gear ratio, lower-viscosity motor oil, and aerodynamic improvements, including a rear spoiler, new hood seals, and air deflectors in front of the tires, and a higher speed threshold for the electric drive.

The company will perform new tests, and expects the 2014 model may get better fuel economy than the 2013 model's new 43-mpg estimate. In particular, Ford thinks the aerodynamic improvements will see a real-world advantage on the highway.

To make amends, the company will send $550 checks to owners of 2013 C-Max Hybrids to compensate them for extra fuel costs. Lessees will get $325.

Of 315 cars we've recently tested, we found that most get within one to two mpg of their EPA estimates. But hybrids were a big exception, with more than half falling short by 10 percent or more. Other hybrids made by Ford, including the Fusion Hybrid and the Lincoln MKZ Hybrid, fell the farthest from their EPA estimates in our tests. So while assigning fuel-economy ratings based on similar vehicles has been accurate enough for most cars, we don't think it's good practice for hybrids or for cars as different as the Fusion and the C-Max.

The EPA is investigating the fuel economy claims for the C-Max and other Ford hybrids. We believe they ought to find ways to better estimate the real-world fuel economy of hybrids, and update their testing requirements to hold automakers' accountable for providing consumers with accurate estimates.

Visit our guide to fuel economy, with tips to save fuel now and lists of the most fuel-efficient cars.

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