Chevy Volt's 'Mountain Mode' is Vastly Underrated, Yields New Driving Strategies

By · May 13, 2011

Chevrolet Volt

The Chevy Volt has been out for a several months now, and it's been reviewed nearly to death—with the vast majority of those reviews being positive. We've even reviewed it in many different ways here on PluginCars.com.

Yes I've driven it quite a bit already myself, but recently I had the opportunity to use it as if it was my personal vehicle for an extended period of time. It was the first time I was able to drive it for more than a few hours or a couple hundred miles at a time. Over the course of five days I drove it on a daily basis to haul my family around, run errands, and even transport a couple of folding tables and six folding chairs back from one of those big box stores. I also took it on a 300+ mile road trip over the Cascade Mountains from where I live in central Washington to Seattle and back.

While the car was certainly everything many other reviewers have raved about (including myself)—quiet, fun to drive, and comfortable—the part of that time that I learned the most was when I drove over the mountains. For one, it was the only time I ever used gas the whole time I had the car. But more importantly, I discovered a very useful driving strategy for long hauls with the Volt that may have been covered elsewhere, but I haven't seen it and it seemed important to bring up.

Mountain Mode is a Great and Underrated Volt Feature

For those that don't know, the Volt has three driving modes to choose from: Normal, Sport, and Mountain. Normal and Sport are pretty self-explanatory, so likely the vast majority of people will just plop it into one of those modes and leave it there based on their driving preferences. But that mysterious Mountain Mode is probably being left alone more than it should. In fact, some very prominent Volt proponents have even gone so far as to say they hardly find a reason to use it at all.

But in my experience, Mountain Mode is extremely useful even for long drives without mountains.

At its root, Mountain Mode is meant to force the Volt to switch from 100% battery-powered mode to charge-sustaining mode (where the engine is burning gas to generate electricity, and sometimes even powering the wheels directly—basically acting as a hybrid) long before the battery is fully drained. GM engineers have said this is to preserve battery power to help get the car up steep slopes with an assist from the electric motors—hence the name "Mountain Mode." In contrast, in both Normal and Sport modes, the car will use up every last drop of stored battery power it can before switching to charge-sustaining mode.

So how is Mountain Mode useful for driving long distances even if there are no mountains? The Volt has a higher fuel economy when driving at highway speeds in charge-sustaining mode than when driving in the city in the same mode. The EPA officially gave the Volt a 35 city/40 highway mpg rating without using stored battery power, but in my experience that charge-sustaining fuel economy on the highway was closer to 43 mpg (yes, that's calculated without any grid-filled battery input). Given that when you get to your destination, there will likely be several miles of driving at city speeds, it makes sense to be able to do that in 100% electric mode if possible, instead of using fuel at the lower fuel economy. Unfortunately, if you drive in Normal mode, by the time you get to your destination you will have used all of those stored electrons to push the car along the highway at high speeds.

Unlike charge sustaining mode, the 100% battery-powered mode is much more efficient at lower speeds in the city. Using electrons to push the car along with all that wind resistance at higher speeds just doesn't make much sense. Some plug-in hybrids, such as the BYD F3DM, allow the driver to switch back and forth between all-electric and hybrid modes at will—and Volvo has made it a core feature of its upcoming V60 plug-in hybrid. Unfortunately, the Volt doesn't have a button that forces it to switch between battery-powered driving and charge-sustaining hybrid driving, but Mountain Mode can act as a proxy.

How does it Work?

First, estimate how much low speed driving you'll do at your destination—we're talking rough ball-park. Assume the Volt has about 30 miles of all-electric driving range at low speeds. Once you use up the battery charge to the point where you have only a few more miles left in the battery than you'll need to drive as an all-electric car at your destination, switch the Volt from Normal Mode to Mountain Mode. Within a few miles the car will switch over to charge sustaining mode, leaving your battery loaded with electrons. When you get to your destination, simply switch it back to Normal Mode and the car will return to all-electric driving.

When I left for Seattle on my long trip, I kept the car in electric mode until I used up about half of my battery—approximately 15 miles—which got me out of the city and about 10 miles down the highway. At that point I switched to Mountain Mode and within three miles my Volt test car switched over to charge-sustaining hybrid mode. I soon entered the mountains and the car did use some battery power to get me over both passes, but for the most part it was regenerating far more than it used on the way down the hill (another strategy here is to put the Volt in in "L" instead of "D," which provides a lot more aggressive regenerative braking). On the downhills I hardly used the car's physical brakes at all.

When I reached Seattle, I had actually regenerated enough energy to add about five more miles to my in-city driving range, for a total of 17 miles of all-electric city driving. It felt great to be driving in the city on electrons, saving fuel from being burned when it's least efficient and not emitting any pollution at ground level where it can do the most harm.

For me this was a chance discovery when I accidentally flipped it into Mountain Mode at the right time and realized very quickly how useful it could be. If I owned a Volt I'd be using this feature a lot more than it's typically given credit. Hopefully the strategy will help you out too. Give it a try and let me know what your results are—or perhaps you've been doing this all along?

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