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Prius plug-in displays battery of good points; For short trips, who could ask for more?
By James R. Healey, USA Today
January 18, 2008
DETROIT -- Seventy-one miles per gallon.
That's what the trip computer read after a 4-mile loop through downtown and a short freeway blast in a prototype of the Toyota Prius plug-in hybrid.
Skip the freeway run, go lighter on the throttle downtown and the reading could have been infinite, because the car would have stayed entirely on battery power, never tapping its gasoline engine for help.
The best of the current, regular hybrids -- the Prius non-plug-in variety -- has mileage ratings in the mid-40s.
How they differ:
*Regular hybrids blend the output of an electric motor and gasoline engine to save fuel. Their batteries are recharged when you slow or stop the car, a process called regenerative braking that turns the electric motor into a generator. Their gasoline engines supplement recharging if regen is insufficient.
*Plug-in hybrids have more battery packs and a charger. Plug the car into an electric outlet -- three or four hours is enough for this prototype -- and it goes farther without the gasoline engine.
No automakers offer regular-production plug-ins yet, though several are under development.
Short trips are the forte of plug-ins. The energy stored when plugged in is enough for several miles on batteries alone. Toyota says the extra battery pack in the plug-in Prius, mounted in the spare-tire well, should be good for about 7 miles. Stay in that range -- a commute, urban errand, quick trip to basketball practice -- and you can drive on batteries only, using no gasoline and expelling no pollutants.
Of course, if you take into account emissions from the powerplant generating the electricity to recharge the battery, the picture gets murky. If that power comes from hydro-electric dams or nuclear or natural gas plants, Toyota says emissions are cut. But not for the USA overall, Toyota says, because half our power comes from coal-fired plants.
Averaged across the USA, "There's very little (emissions) benefit" compared with a current Prius hybrid, says Jaycie Chitwood, senior planner at Toyota's advanced technologies unit in the USA.
The test car was one of eight in the USA and among 400 Toyota will field for real-world trials next year.
At the start of the test drive, the car's instruments showed enough charge for 5 miles on battery only. The Prius reverted to normal gasoline-electric hybrid mode just as the 4-mile loop ended, signaling the extra battery was nearly depleted -- and that driving had been a bit vigorous.
The only apparent differences between the prototype plug-in and a regular Prius:
*An electrical socket hidden behind what looks like a gas-filler flap on the right-rear fender.
*A dashboard monitor to track electric-only travel: how much farther you can go and how hard you can push the vehicle before dipping into gasoline power.
The prototype behaved about like any other Prius -- which is a good thing. Prius hybrids are popular because they are good cars, regardless of what's powering them. Fuel-saving benefits are a bonus.
They have extraordinary interior room for their size. Their hatchback lets you easily load. Their interiors fit together well and offend neither eye nor hand.
As expected in a Prius, seats were comfortable and the ride pretty composed. Corners can't be taken with the brio of a sports sedan, but control is satisfactory.
The electric power steering feels slightly artificial, but the assist is about right for routine driving.
The plug-in, like other Priuses and most hybrids, shimmies when the gas engine kicks in. Otherwise, the test car was smooth, quiet and punchy. The extra battery pack boots total gas-electric output to 136 horsepower vs. 110 in the normal Prius, says Toyota, enough to push the plug-in's extra 220 pounds.
Electric motors deliver peak torque -- low-speed power -- the instant they start. Most any electric car can embarrass a gasoline muscle car at a green light.
"Just because they're 'green' doesn't mean they can't be fun," says General Motors' Tony Posawatz, head of GM's plug-in-vehicle development.
The quiet, irresistible urge of the prototype was luxurious, as if road issues weren't real. Toe lightly into the throttle and feel no-hassle response from the motor. Slight whine is heard from the motor, but only because the rest of the car is so quiet. Typical of a hybrid.
Full-throttling onto the freeway put the extra battery power to good use, flinging the prototype to proper speed briskly. The plug-in can stay in electric-only mode on level roads up to 62 mph, Toyota says, vs. 20 mph in the regular Prius.
Plug-ins seem wonderful for short trips and would do no worse than regular hybrids on longer trips.
But Chitwood warns they'll cost more; she wouldn't guess how much. Today's Prius hybrid starts at about $22,000. Price partly will be dictated by how far people insist on going on only battery power. Greater range raises the costs of the batteries and charging gear.
But every mile on battery power is a mile without a drop of petroleum or tailpipe emissions.
Some is better than none.
Toyota Prius plug-in hybrid
*What is it? Plug-in version of the popular gasoline-electric hybrid. An additional battery pack with a plug-in apparatus allows battery-only operation for several miles before gasoline engine kicks in. Four-door, front-wheel-drive compact hatchback with midsize interior room.
*How soon? A few in demonstration fleets now, more coming late next year as Toyota pushes to get 400 into service worldwide to collect data on charging and other issues.
Don't expect regular-production versions for at least two years, probably longer.
* How much? Plug-ins will be priced higher than regular hybrids because of their extra batteries and charging hardware, but Toyota hasn't forecast a price premium.
Regular Prius starts at about $22,000.
*What's the drivetrain? Same as regular Prius, with another battery mounted in a spare-tire well: 1.5-liter, four-cylinder gasoline engine and an electric motor, both driving though a continuously variable transmission using planetary gears.
Total combined power listed as 136 horsepower (vs. 110 in current Prius). Toyota doesn't provide combined total torque figure.
*What's the rest? Features, furnishings are same as regular Prius, which is listed at www.toyota.com.
* How big? Prius is 175 inches long, 67.9 inches wide, 58.7 inches tall on a 106.3-inch wheelbase.
Weight of plug-in is listed as 2,992 pounds, 220 pounds more than regular version.
*How thirsty? Toyota says the plug-in will go about 7 miles on battery power only, before switching to regular gasoline-electric hybrid mode.
Uses no gasoline in battery-only mode.
Regular Prius hybrid rated 48 miles per gallon in town, 45 on the highway 46 in combined driving.
Plug-in test car recorded 71.3 mpg in a 4-mile route that included a short, fast freeway section.
The drive depleted the plug-in battery, so fuel mileage would have begun dropping fast in additional driving as the gasoline engine cycled on during normal hybrid mode.
*Overall: Very promising technology, but how soon and how much?
What stands out
*Quick: Extra battery provides extra scoot.
*Comfy: Just like regular Prius, which it basically is.
*Stingy: Uses no gasoline for the first few miles.
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