Katie Sebastian accuses her friend Evan Hirsche of getting better mileage because he lives in Bethesda, Md., and has flatter everyday trips than she encounters in nearby but hilly Takoma Park. She suspects the Hirsches of taking frequent long drives out of town, which also helps them.
“They claim they haven’t been out of town in a while,” she said, “but I know they have.”
Hirsche retorts: “It is well known that Katie is a lead-footer.”
Their friendly rivalry stems from the Prius effect. Both drive a Prius, the Toyota hybrid with an elaborate dashboard monitor that constantly informs drivers how many miles per gallon they are getting and whether the engine is running on battery or gasoline power. That can change driving in startling ways, making drivers conscious of their driving habits, then adjusting them to compete for better mileage. (Sebastian has 41 mpg, Hirsche 43.)
The Prius, and other hybrids with similar displays, has triggered on-the-spot learning that has the potential to change energy-consumption habits. The implications go far beyond the family car, with devices for the home offering ways to encourage significant change in energy use.
“Once you start making fuel consumption more visible, you have something that comes to the forefront of people’s minds instead of lurking in the background,” said Sarah Darby, a researcher who studies energy feedback technologies at the University of Oxford’s Environmental Change Institute. The monitors “show the consequences of your actions,” she says. “This gives you feedback that alters actions, and encourages you to try and improve things.”
In the Prius and other hybrids with energy displays, drivers can see what specific actions mean for their mileage. In some ways, it is like children learning to color in between the lines, with the teacher standing over their shoulders. Aggressive acceleration after a stoplight – that’s bad. The monitor will show mpg going down. Suddenly slamming the brakes – also bad. Coasting to a stop – good. That tactic lets the engine shut down, saving gas. Hills – oh, they are real bad.
Tom Igoe, a physical-computing researcher at New York University, said the Prius mpg display is one of the best examples of technology “where green meets information systems.”
“For a long time,” he said, “we have known that people will change their habits if they are exposed to feedback in real time.”
Now companies are introducing products that do for the home what the monitor in the Prius has done for the car. The Kill a Watt plugs into a wall and accepts plug-ins from appliances, showing exactly how much energy is being consumed. Sebastian recently bought one: “We want to know where our electricity is going.”
The Wattson, a console designed by a British company, wirelessly connects to a home’s energy meter and displays how many watts of electricity the house is using. If the console glows blue, less electricity than normal is being used. If it glows red, it’s the opposite.
Massachusetts company Ambient Devices, a spinoff of MIT’s famed Media Lab, is testing, in connection with several large U.S. utilities, a device called the Orb. It is a small frosted-glass ball that changes color based on how much demand is on the electricity grid. You can put it anywhere in the house, like a piece of modern art. When demand is high, consumption costs more, and the Orb turns red. When it’s low, the cost falls, and the Orb turns green. Homeowners can adjust their consumption accordingly, perhaps not washing the dishes when the energy grid is being taxed and the Orb is red.
“They are as easy to use as a clock,” said Mark Prince, a vice president at Ambient. “You just look at them.”
Darby, the Oxford researcher, said energy feedback systems made a brief appearance during the 1970s and ‘80s, but after the oil crisis subsided and the era of cheap gas returned, they hit the shelf. Now that fuel prices are soaring again and consumers are more interested in green behavior, the focus on the displays has come back.
Although other hybrid cars also have mileage displays, the Prius is the one spawning intense rivalry, because of its strong brand as a hybrid-only car. It has dominated the hybrid market and its drivers outnumber all other hybrid drivers combined.
Instead of being content with the 48 miles per gallon in the city and 45 miles per gallon on the highway – 2008 EPA standards for the Prius – some drivers try to find ways to get far more and go to extremes to do so. When Lee Peterson’s wife wanted to borrow his Prius, he barked “No.” His wife was baffled. He said: “You’re gonna screw up my mileage.”
Peterson, an Ohio retail consultant and former Jeep driver, had never been interested in mileage. But when he got a Prius, he became fixated with stretching his mileage as far as possible. Peterson keeps track of his mileage the way golfers chart their handicaps. His record back when his wife wanted the car was 57.4 miles to the gallon. But the monitor put him at 58 – more than double the 27.5 mpg that non-hybrid passenger cars are required to get in the United States. He had a quarter-tank to go.
“I was going to break my record,” Peterson said, but only if his wife steered clear of his wheels.
Peterson tries to avoid a big hill on his way to work. “If I go up the hill, it really puts stress on the car,” he said. “That’s when you start to do the weird Prius thing. I’m looking at the display, and I’m getting 10 to 15 miles to the gallon.”
He didn’t think about the hill when he drove his Jeep. “It’s just knowledge,” he said. “Now I have it. Knowledge is king.”
Some hybrid drivers are so infatuated with their mpgs that they call themselves hypermilers and battle with one another down to the tenth of a mile. Tony Schaefer, a Chicago hypermiler, tracks his mpg for every tank, then posts his results online to a Prius chat group. He has done this for four years. A recent tank finished on April 28 got 66.9 mpg.
In the notes section of his results, Schaefer wrote: “First 60+ tank of the season. Was at 67.8 but then bad weather.” The tank lasted 14 days. His 12-month mpg average is 60.11, up from 59.79, recorded after the previous tank. His lifetime mpg average is 53.2.
Michael Gomez, an interactive designer in Austin, Texas, has started a Web site called Green Interfaces that tracks displays such as the Prius’. “The best interfaces are the ones that make it interesting and fun,” he said. “The competitive driving thing some people are doing means they are making a game out of it, and that’s a pretty good test for a good design – do people start to play with it?”
Schaefer described Prius driving as just that: “It’s like playing a game against yourself. You want every tank to be better than the tank before.”
Peterson, for the first time in his life, is taking his time.
“It has totally changed my driving in that for the first time I’m completely cognizant of how the car works.” He’s also aware that his driving may irritate the unenlightened.
“People get mad driving behind you,” Peterson said. “They think, ‘There’s the geek.’ “
But that’s fine with him: Gas is topping $4 a gallon, and he’s getting double the mileage they get.
“I’m totally hooked.”