A few months back, we noted that our long-term Kia Sedona wasn't quite holding up its end of the bargain when it came to meeting its fuel economy numbers. The EPA says our particular version -- there are different numbers for different models -- should be getting 18 mpg in the city, 25 mpg on the highway and 21 mpg combined; that's about the same as the Toyota Sienna and the Dodge Grand Caravan. However, our monitoring showed us getting a bit more than 17 mpg in mixed driving.

Obviously, driving habits, terrain, load, and a lot of other factors come into play when looking at fuel economy. For example, some of us tend to have lead feet even when driving something as practical-minded as a minivan. But the Sedona's numbers were still surprising, since despite our lead feet other minivans like the Honda Odyssey generally return numbers much closer to the EPA estimates.

The Eco experiment

So, we tried an experiment. Since October and through the month of May, we've been driving our long-term Kia Sedona SX in its fuel-saving "Eco" mode. This reduces both throttle sensitivity and the transmission's willingness to downshift, all with the goal using as little gasoline as possible. It makes a noticeable but subtle difference, with the van feeling lazier toward throttle inputs. We wound up racking up nearly 6,000 miles in Eco mode, and were eager to see the results.

Well, the results are in and...they're basically the same. In fact, with Eco mode engaged, our running average was 0.1 mpg less than without it, although it's important to note that's a statistically insignificant difference. Still, it raises the question: What's going on here?

There are a few things, one definite, some speculative. First, while the Sedona weighs about the same as the Honda Odyssey, it lacks the Honda's active fuel management system that shuts down some cylinders during light throttle or cruise. We generally see something closer to the EPA's combined score of 22 mpg when we've driven it, and it's likely the active fuel management system plays a role.

Overcompensating perhaps?

Second, one of the curiosities of technologies like the Sedona's Eco mode is that it might be counterproductive in some situations. It's possible that, because of the Eco mode's lazy-feeling throttle, that we’re more inclined to floor it than we otherwise would be. Maybe no big deal, but miles of thoughtful driving can quickly be undone with just a relatively short mash of the gas pedal. Note that we're speculating here since we don't have a long-term map of our throttle usage over the test period.

A couple other things come to mind. The Sedona's tires, for example, might have a more aggressive tread that is less conducive to saving fuel; it wouldn't be a huge difference, but an incremental one that could have an impact over the long term. The sloping face of the Honda might be more aerodynamic than the blunt-nosed Kia, and since neither company posts drag coefficient numbers, we're left to wonder.

Regardless, while the Sedona has definite strengths -- it's pleasant to drive, looks good inside and out, is very comfortable and quiet on the highway -- it's clear that unless you're already extremely light on the gas, fuel economy is not one of its strong suits.

See past reports for our Long-Term 2015 Kia Sedona...


Long-Term Update: Design

Long-Term Update: Utility

Long-Term Update: Powertrain

Long-Term Update: Comfort

Long-Term Update: Moving Day

More 2015 Kia Sedona...

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