“Dave and Karen Anderson are likely the first Whidbey Island residents to own a hybrid Toyota Prius.Jim Larsen/staff photoThe future has arrived on Whidbey Island, at least as far as automobiles go.Dave and Karen Anderson of Clinton are probably the first islanders to drive home with a hybrid Toyota Prius, which powers itself with batteries and gasoline.On a trip to Langley last week, passerby Mindy Magnusson asked the Andersons a question they have heard many times since they started driving the Prius earlier this month. How far can you go before you have to plug it in?The answer is you don’t. The Prius isn’t an all-electric car, which is a dream that car makers have often promised but never produced in quantity. Instead, the Prius uses a combination of a battery-powered electric motor and a traditional gas engine.The gas engine charges the battery, meaning there is no need to charge it from a socket. And although not perfectly green, the Prius pollutes far less, and gets far better mileage, than other automobiles.According to Toyota, the Prius cuts carbon dioxide emissions by half (carbon dioxide is suspected as a leading cause of global warming), and the car produces one-10th the amount of several types of poisonous gases.Dave Anderson plans to use the car for his frequent trips to Olympia where he is a state representative. The hybrid is rated at 45 miles per gallon on the highway, 52 in the city. That’s opposite of most cars, which get better mileage on the highway. In the city, the Prius spends more time on battery power.We ordered this thing months ago, Anderson said. It’s peppy, but you get obsessed (with mileage).Karen agreed. I got 70 miles per gallon coming in to Langley, she said. Downhill. A large mileage readout on the dash is hard to ignore, as it electronically reports the precise mileage of the moment — from zero to 100 miles per gallon. Going up the Anthes Street hill in Langley the car gets 28 miles per gallon; going down, it hits 100. On the level, it pushes past the 50 mpg mark.Attractively designed and roomier than it looks, the Prius’ most unusual attribute is its lack of noise. It idles on battery power and is absolutely silent; moving down the road, passengers can’t tell whether the battery is being used or the gas engine is engaged. Want to know? Just push a button, and a new display on the screen produces a colorful energy flow chart.The car cost $20,500 plus tax and license, which is less than it costs to manufacture. Toyota reports that the car costs between $35,000 and $40,000 to build. The discount, observers suspect, is aimed at obtaining good publicity and promoting the technology.The Prius’ batteries are not easy to find — they’re accessed through the roomy trunk — nor are they something that a backyard mechanic should tamper with. But Toyota is confident enough in the design to back it up in writing. It’s guaranteed for 100,000 miles or eight years, Dave Anderson said.Driving down the road, Dave couldn’t resist some backseat driving as Karen stepped on the gas to show the car is not sluggish. You’re wrecking your mileage, Karen, he said. She laughed, and admitted that she too hated to lose any mileage to the demonstration of power.Wherever the car is parked, it attracts the curious. I’ve been reading about it in Car & Driver for ages — it’s great to see one, said James Enslow, who was passing by in Langley.The Andersons ordered the car in June before gas prices skyrocked. Now, they don’t have to make nearly as many stops at those $1.85 a gallon pumps. The 12-gallon tank gives it a range of up to 800 miles.Honda unveiled a two-door gas-electric vehicle earlier this year, but Prius has the four-door market to itself until the competition catches up. “