From its inception, the Chevy Volt was designed to travel 40 miles without using a drop of gasoline. General Motors drew the line in the sand, citing studies that show the majority of US drivers, on average, travel less than 40 miles per day. In a refrain repeated over and over again by GM executives, and bandied about in advertising, the company has held firm to its promise of 40 miles of electric driving before the small onboard engine would be called into service.

However, one year prior to its release, journalists are discovering that the Volt will fall short of the 40 miles of all-electric range under a number of conditions.

Edmunds’ John O’Dell yesterday took a brief test drive of the Volt, and grilled Volt Chief Engineer Andrew Farah. O’Dell discovered that the 2011 will indeed deliver 40 miles of battery-only range on the EPA city cycle, a driving circuit with an average speed of just under 20 mph. But the Volt’s battery range will be diminished under these conditions:

  • Aggressive acceleration
  • Sustain high-speed driving
  • Exceptionally hot or cold ambient temperatures
  • Driving in hilly or mountainous terrain

O’Dell writes, “If you pull out of the driveway with a full charge, hop on an uncrowded freeway and motor away at 65 miles an hour, you won’t get 40 miles on battery power alone.”

Does It Matter?

From the beginning, the 40-mile number seemed arbitrary. After all, how many Volt owners are going to complain if the engine comes on after 38 miles or 35 miles? The Chevy Volt is expected to be the only mainstream relatively affordable plug-in hybrid on the market—it goes on sale in late 2010—with anywhere near 40 miles of all-electric range for quite some time.

But if the Volt does fall short of 40 miles of electric range, and 35 or 30 miles proves to be enough for satisfied owners, it begs the question of how much all-electric range is needed after all. Earlier this year, researchers from Carnegie Melon University found that the extra cost and weight of batteries needed for 40 miles of all-electric range are cost-prohibitive. Researchers said, “Large-capacity plug-in hybrids sized for 40 or more miles of electric-only travel are not cost-effective in any scenario.”

The Volt is expected to cost about $40,000. Could GM reduce the cost of the Volt—and potentially sell more units maybe even at a profit—by downsizing the battery pack to allow for 30, 20, or even 10 miles of all-electric range? Does it strike a better balance between cost and EV-range to tap into gasoline when needed throughout the driving cycle—the “blended” approach expected from Ford and Toyota, as well as GM’s own future plug-in hybrid SUV? Or maybe those who must have a long all-electric range would be happy to pay $10,000 less and give up the ability to take their electric car on long-range trips? The Nissan Leaf is expected to sell in the low $30,000s and will never use a drop of gasoline, because it’s purely electric and doesn’t have a gas engine.

The new era of plug-in hybrids and electric cars will bring these questions and many more. Perhaps the biggest question—at least for GM one year before the release of the Chevy Volt—is whether or not it should continue to make the 40-mile claim when it might not be true for many of its owners.