The automobile has improved in many ways since Henry Ford trotted out the first Model T's 100 years ago. Fuel economy, however, is not one of them.
The original horseless carriage got about 20 miles on the gallon, the same on-the-road fuel-burning efficiency that the nation's fleet has hovered around since 1980, according to Jeff Alson, a senior engineer with U.S. EPA's transportation and climate division.
But climate change and oil supply concerns are signaling an end to the era of incremental technological change and an about-face of priorities, he said, speaking at an event at George Washington University. "The future is unlikely to be like the past," Alson said.
With automakers clinging on for their lives and President Obama pledging to remake them in a more fuel-sipping image, plug-in hybrid electric vehicles are one sign of hope in that future. Obama has said he wants 1 million on the road by 2015.
General Motors Corp.'s Chevrolet Volt, scheduled for production in limited numbers for 2010, will be one of the first major plug-in models to test the market. "Everything else is up for grabs in the current restructuring except for this," said GM's Keith Cole, director of legislative and regulatory affairs, last week.
But companies are also becoming antsy about the high expectations that will greet the initial release of these models. "The one thing we can't have is disappointment with a new technology. That will doom the technology," said Tom Stricker, a director at Toyota Motor North America Inc.
Toyota is planning a limited introduction of a plug-in version of its Prius model to commercial fleet owners, with 150 coming to the United States by next year. Stricker is wary of repeating the company's experience with its conventional hybrid Prius.
Toyota's initial sticker shock
Originally, EPA gave the Prius hybrid a 55 miles per gallon rating on its window sticker. But when, for the 2008 model year, the agency adopted new methods to account for more real-world driving factors, such as cold weather and faster accelerations, hybrids got hit the hardest; the Prius' rating dropped to 46 mpg, for example. Class action lawsuits from angry customers followed.
Putting a fuel economy estimate on the plug-in hybrids will be an even more complicated process. That's largely because, with plug-ins, even more depends on drivers' individual behavior. How much and how often the car is charged, how far it is driven between charges, and the weather's effect on the battery all contribute to individual variations in the degree to which a particular plug-in relies on its electric mode.
Although various automakers, also including Ford and Saturn, are taking different technological approaches, all plug-in hybrids rely on burning backup fuel eventually.
Earlier this year, using one of several available conversion kits marketed by outside companies that void the manufacturer's warranty, Consumer Reports turned a Toyota Prius hybrid into a plug-in model.
For the first 35 miles of driving, the testers found that the converted Prius jumped from 42 to 67 mpg, a major gain but much lower than the 100 mpg that the conversion company had claimed. Meanwhile, Google.org, the philanthropic arm of Google Inc., in its own tests of a Prius conversion, has gotten an average of 94 mpg.
Stricker, of Toyota, said he has seen a wide range of numbers thrown around, anywhere from 65 to 110 mpg.
"We have to be very careful to manage expectations of what the consumers perceive going in," he said. "If you look at current real-world data, albeit on conversions, it's not what we hope it will eventually be."
EPA at work, using 2 different formulas
Electricity is not free, either, and some fuel-use estimates attempt to weight the energy cost of the juice the battery takes from the wall socket. Gabriel Shenhar, program manager for Consumer Reports' auto testing center, said that in its test model, it calculated that the fuel economy dropped to the equivalent of 53 miles per gallon when electric consumption was taken into account.
The Volt, by contrast, is an extended-range vehicle designed to run solely on its battery for the first 40 miles of use, enough to satisfy three-quarters of Americans' daily driving needs -- but EPA will still need to evaluate these claims and somehow translate them into a fuel usage number.
Employees at EPA's National Vehicle and Fuel Emissions Laboratory in Ann Arbor, Mich., are now working on the problem of how to accurately gauge these vehicles' fuel use, said Alson.
The facility does fuel economy testing and verification using two different formulas: one for the window sticker that consumers see, and one to report to the Transportation Department to calculate a manufacturer's fleetwide fuel economy average -- the basis for federal corporate average fuel economy, or CAFE, standards.
Mark Duvall, director of electric transportation at the Electric Power Research Institute, noted that how the agency calculates the contribution of plug-in hybrids to CAFE standards is probably the decision of larger consequence.
When averaging fuel economy across a manufacturer's entire fleet, relatively few plug-in hybrids could potentially skew the average considerably, agreed Matt Mattila, a consultant for the Rocky Mountain Institute's Project Get Ready, which helps cities prepare to adopt electric vehicle technologies.
Mattila said that it is up to the automakers to educate consumers that the plug-in hybrid will not be the right option for everyone, and that whether it is right for them would depend on their driving patterns.
The car companies are blunter: "The real question is, can we get anyone to buy it?" asked Stricker. If the fuel saved with a plug-in hybrid compared to a conventional hybrid doesn't outweigh the added cost -- and with the price of batteries, that added cost is significant -- then no one will buy the car.
They also fear being held hostage to volatile oil prices. "If gas is below $2 a gallon, we ask why anyone would do this," said GM's Cole.