More than a million hybrid-electric cars are on the road. Using gasoline engines to turn their wheels through an artful mix of mechanical and electric power, hybrids are such an unexpected market success that they’ve attracted criticism, some perhaps encouraged by jealous rivals.

Learning to Drive a Hybrid

A leading myth holds that hybrids save little fuel and are far less efficient than their USEPA miles-per-gallon (mpg) ratings. This fallacy originated with Consumer’s Reports, whose uniform test methods discriminate against hybrids, and the New York Times, which made the same error but proposes to retest to determine how much better hybrids perform when driven optimally.

How should you drive a hybrid? First, if you’ll need to stop up ahead, start braking early (but gently) to maximize “regenerative braking,” which in a good hybrid like a Toyota Prius recovers energy with a wheel-to-wheel efficiency of two-thirds. Second—contrary to ole, pre-hybrid high-school Driver’s Ed courses—hybrids’ mpg rises with rapid acceleration, for two reasons: (a) The engine is more efficient at relatively high speed and torque, so it uses less fuel when accelerating to cruise speed briskly for a short period than gently for a long period, and (b) Fast acceleration gets boosted by the electric motor, using recovered braking energy to save even more gasoline.

EPA Ratings: How Accurate?

A second myth is that in realistic driving, hybrids fall short of their EPA-rated mpg by more than nonhybrids do. Just the opposite is generally true because most hybrids have more efficient air conditioners and other accessories than nonhybrids. In practice, well-driven hybrids get far closer to their EPA ratings than well-driven nonhybrids can. A properly driven Prius gets about 52–55 mpg (rated 55); if your Prius gets in the 40s, review the instructions above and use its mpg gauge to tune your driving patterns. My Honda Insight hybrid gets 62 mpg (rated 64) even though it’s 3/4 on snow tires, often in snow, and usually in low temperatures that cut battery efficiency.

Hybrids Don’t Have to be Slow

Third, some environmentalists criticize a few hybrid models that offer muscular performance. For nonhybrids, that would be a valid concern, because for a given weight, faster acceleration requires bigger engines that run less efficiently all the time. (A typical car uses only 1/6 of its full power in highway cruising and a few percent in the city, halving its engine’s efficiency.) But hybrids’ electric motors deliver high torque while making the gasoline engine smaller and running it more efficiently. This permits faster acceleration while raising fuel economy.

Debunking the Hummer Myth

Fourth, “Dust to Dust,” published in December 2006 by a mysterious and anonymously funded market research firm, was publicized by some journalists who should have known better. Without revealing its data or methods, it claimed that a Prius is environment-ally worse than a Hummer. It’s junk science. Its authors should be ashamed of themselves. Prius owners can rest content.

But stay tuned for more solutions!

Amory B. Lovins, Chairman and Chief Scientist, Rocky Mountain Institute