Getting to the bottom of Ford's hybrid fuel economy controversy

© Eric Rogell

Recently I posted a test drive review of the C-MAX, Ford's new hybrid and part of their stated push to offer the most fuel efficient, and most affordable, hybrids and EVs in the US. In my post, I quoted Ford's EPA-certified mileage findings for the car as 47 mpg city, 47 mpg highway and 47 mpg combined. Some readers took issue with these numbers, pointing to online complaints from C-MAX owners who are claiming their actual mileage is dramatically less. We even posted a story about this issue last December, saying that the EPA is planning to test those figures.

How can the EPA be testing their own "certified" numbers? Simple: The EPA only has the resources to actually test a small portion of the number of new vehicles that are released each year. Just 15% by some accounts. The other 85%? The EPA relies on the manufacturer's own findings, trusting them to be accurate. In this case, we assume the C-MAX wasn't one of the vehicles tested, and the EPA wants to put the car to the test. We'll keep you posted on their findings.

© Ford

In our December story, a Ford spokesman told us:

Early C-MAX Hybrid and Fusion Hybrid customers praise the vehicles and report a range of fuel economy figures, including some reports above 47 mpg. This reinforces the fact that driving styles, driving conditions, driving speed, driving conditions and other factors can cause mileage to vary.

I wanted a more thorough explanation, so I spoke via email with Todd Nissen, Sustainability Communications Manager at Ford, and asked him HOW these factors can influence our fuel economy, and what the "other factors" are that can effect results. Here's what he told me:

For example, if you drive 75 miles per hour instead of 65, you would lose about 7 mpg in our new Fusion Hybrid. Similarly, if the outside temperature is 40 degrees instead of 70, you would lose about 5 mpg. And if you have very few break-in miles on the vehicle instead of 6,000, you would lose another 5 mpg. So you can quickly see how a customer could experience a range of up to 17 mpg (less) in what many may view as fairly normal conditions.

Does this mean that in order to enjoy optimum mileage you have to first drive your car over 6,000 miles, drive the speed limit and only drive in warm weather? Apparently that is the case. Do people normally drive this way? As I mentioned in my review, I rarely achieve the EPA's numbers. I'm pushing the car to test its abilities, not it's mileage. But a pair of other C-MAX testers did "hypermile" during their test, driving as efficiently as possible, and they came fairly close to 47 mpg in city traffic. So, yes, driving style does have a lot to do with what fuel economy you'll ultimately experience.

But we are still not satisfied. So I've arranged another test drive of the C-MAX hybrid, and I'll have the vehicle for a week. During that week, I'm going to drive it as I think any normal, reasonable person would drive. I'll have a video camera running much of time as well, to record the numbers and the EcoGuide that tells drivers how efficiently they are driving. And we'll see what I experience over that time. Stay tuned for our findings.

See also: Chevy Volt and Cadillac ELR could get downsized 3-cylinder engines

Tags: Hybrid Cars

WHAT'S HOT ON FACEBOOK