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2012 Toyota Prius Plug-in Review By Carey Russ

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2012 Toyota Prius Plug-in

After a dozen years, three generations (in the U.S, one more in Japan), and over a million examples sold, the Toyota Prius gasoline-electric hybrid is hardly advanced technology for early adopters. It's solidly mainstream, even though it continues to evolve.

Part of that evolution is an expanded model lineup, with the core sedan, now called the Liftback, joined in the past year by the larger Prius v, smaller Prius c, and nearly identical-looking Plug-in Hybrid.

Of that group, the Plug-in Hybrid is the most technically advanced, and presages future evolution for the Prius. But what is meant by "plug-in hybrid" and isn't the rationale behind an internal-combustion/electric hybrid vehicle independence from external charging?

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Think of a plug-in hybrid as a vehicle that combines the best features of a hybrid and a pure electric vehicle (EV). It can operate further on electricity than a regular hybrid, and that electricity can be acquired from an external source -- that may be less expensive than gasoline. When the plug-in battery's charge drops too low, no range anxiety -- the internal combustion engine will recharge the battery pack and help run the car, just as in a regular hybrid.

The regular Prius models use a nickel-metal hydride (NiMH) battery pack that is not amenable to external charging. Older Priuses have been converted to plug-in operation by independent modification firms, but there's no factory support if the modifier should go out of business. Toyota itself had a test program, with 125 2011 Priuses factory-modified for plug-in operation. Those cars had extra lithium-ion (Li-ion) batteries in addition to the NiMH battery pack for plug-in operation. I had one as a test car for a week last year, and found it to be little different from a regular Prius with the exception of greater EV range and easy at-home recharging.

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Experience with that test fleet went into development of the official plug-in model. Which is a bit different from both the prototypes and the regular Prius. In the official plug-in, the NiMH battery pack is replaced by a Li-ion pack of greater capacity than the "add-on" pack of the prototypes. It's lighter in weight than the prototype battery pack, but enables a potentially-longer EV range. When the charge drops to a specified point, the Plug-in Prius reverts to default hybrid mode, identical to a standard Liftback. Because of the lighter battery pack and structural changes including a floor panel made of a reinforced honeycomb-like material, the Plug-in is about 200 pounds lighter than the prototype version, and only 120 pounds heavier than the standard Liftback. The rest of the Plug-in's Hybrid Synergy Drive is the same as the Liftback's, with a 98-horsepower, 1.8-liter Atkinson-cycle four-cylinder gasoline engine, an 80-hp traction motor, and a smaller starter-motor/generator. Maximum system horsepower is the same 134 as the Liftback. Like other Priuses, it recovers electrical energy by regenerative braking, with extra regenerative braking available by moving the shifter to the "B" position.

There are two trim levels, standard and Advanced. The standard model is equivalent in appointment with the Liftback Two, but with additional features from the Three and Four. The Advanced gets a Head-up display, LED headlights, SofTex seating with a power driver's seat, and upgraded audio system, and the Pre-Collision System with Dynamic Radar Cruise Control and the Safety Connect telematics system.

My test car was a standard model with minimal options. Not fancy, but definitely functional -- and lighter than one with all the options so a bit quicker and more economical. The driving experience is identical to that of a standard Liftback with one important difference -- beside the Eco and Power mode switches on the console is one marked HV/EV. As in "Hybrid Vehicle/Electric Vehicle". Default is for the car to start in EV mode and run as such until the battery reached the cutoff point, at which time it reverts to normal hybrid mode. If you'll be driving in a situation that's not ideal for EV mode, like on the highway, defer EV operation until the conditions are better.

Performance is more than adequate, and in Power mode acceleration is surprisingly quick. Using Eco mode most of the time, and EV when most useful, I averaged 53 mpg for my week. Best non-EV mileage was downhill at a slow speed, with well over 100 mpg showing. Of course, going up that hill was not quite like that‚€¶¬ and no matter what your power source, you'll use more energy going up than down.

At $32,000, the Prius Plug-in does command a high (about $7,000) premium over a Prius Liftback Two or Three. That money still buys plenty of unleaded regular so a Plug-in is not for everyone. Yet, as battery technology improves and prices come down, there will be an increasing number of plug-in hybrids. The system works, and well.

Final note -- I had no problem recharging the Plug-in Prius at home. Unplug the dryer, plug in the charger, run the cord out the window to the driveway. And with the charge port repositioned to the right side, less distance to it. If it can work with my 1943-spec house wiring, it should work pretty much anywhere!

APPEARANCE: Differences between a Prius Liftback and Plug-in are minimal. Most apparent is the charge port door on the right rear fender, complementing the fuel door on the right rear. Badging, on the front fenders and tail, is unique, with a plug-shaped motif. There's a chrome panel above the lower air intake in front, and matte silver-finished outside door handles. Blue-accent headlights and LED taillights further distinguish the Plug-in.

COMFORT: Interior differences are even less than exterior. There's a "Plug-in Hybrid" badge on the dash in front of the front passenger. Fit and finish is as expected from Toyota, first-rate. As are the materials, textured hard and softish plastics for most surfaces and carbon-neutral "ecological plastic" for seat foam and some trim pieces. All of the expected conveniences are here, including a navigation system, backup camera, AM/FM/SiriusXM radio, CD changer, and connection for iPods and other external audio players. Plus the Entune multimedia system that allows use of mobile apps with a smartphone. As in the regular Liftback, there's more interior space than might be expected, front and rear. The rear seat folds 60/40 but don't look under the rear load floor for a spare tire - weight savings means runflats or a can of sealant. There is a small compartment under the rear of the load floor for the charger cord.

SAFETY: The Prius Plug-in is a Toyota, so it has the StarSafety System, comprised of vehicle stability control (VSC), traction control (TRAC), antilock brakes (ABS), electronic brake-force distribution (EBD), Brake Assist, and the Smart Stop Technology brake override system. Seven airbags are standard. The Pre-Collision System with Dynamic Radar Cruise Control and Safety Connect are standard in Advanced models.

RIDE AND HANDLING: Because of the new battery pack, weight is increased over the Liftback by about 120 pounds. The suspension is retuned a bit, and and feels softer than a Liftback. The emphasis in on comfort, not performance, and the smooth ride and near-silent operation ensure that. Low rolling resistance tires are meant for maximum mileage, and do have lower limits of adhesion than performance tires. This is an ultra-economical family car, not a Toyota Le Mans hybrid prototype race car‚€¶ and it feels pretty much like a Prius Liftback.

PERFORMANCE: Toyota keeps refining its Hybrid Synergy Drive system to use electric power instead of internal combustion at higher speeds and for longer distances. Even in HV mode, the Plug-in runs silently under electric power more than older Priuses, especially on level ground under light throttle, or downhill. Engine noise and vibration are minimal, really only noticeable when starting from cold. At low speeds in EV mode, the car emits a strange, low-pitched whirring noise, presumably to alert pedestrians, especially blind ones with excellent hearing. Acceleration, especially in Power mode, is more than adequate to deal with short on-ramps and such traffic hazards, and if a newer Prius is acting like a left-lane bandit, blame the operator, not the car. Braking is exemplary, with regenerative braking adding to the four-wheel antilock discs.

But the Plug-in's chief attraction is fuel economy. With an EV range of 10 to 15 miles and a recharge time of three hours (at 120VAC, less for 220), it is possible to rarely use gasoline if the car is used for a short commute or local errands -- especially if charging is available at the destination. Even using gasoline, over 50 mpg is readily achieved. Because it's a hybrid, there is no EV "range anxiety". When the plug-in charge is used up, it reverts to regular hybrid mode. Just don't run out of gas!

Note that in EV mode, the engine will turn on and add power under hard acceleration, as in merging on to the highway. I found that at speeds of 25 mph or less in EV mode, steep hills did not require internal combustion assistance, at least until the battery drained.

What does charging cost? The Plug-in charges at 1 kilowatt-hour (kwh). My electric rate is about $0.13/kwh. Three kwh for a full charge is $0.39. Figure 11 miles (on average) per full charge and that's about three and half cents per mile! Gasoline? For simplicity, $5.00/gallon (yes, that's California designer gasoline) and 50 mpg is ten cents a mile.

CONCLUSIONS: Go further on less fuel and recharge easily at home with the Toyota Prius Plug-in Hybrid.

2012 Toyota Prius Plug-in

Base Price			$ 32,000
Price As Tested			$ 33,151
Engine Type			DOHC 16-valve four-cylinder Atkinson
				 cycle with VVT-i variable valve control
Engine Size			1.8 liters / 110 cu. in.
Horsepower			98 @ 105 rpm
Torque (lb-ft)			105 @ 4000 rpm
Electric Motor			permanent magnet AC synchronous
Horsepower			80
Torque	 (lb-ft)		153
Transmission			CVT combining input from both engine and motor
Maximum combined system horsepower	143
Wheelbase / Length		106.3 in. / 176.4 in.
Curb Weight			3165 lbs.
Pounds Per Horsepower		23.6
Fuel Capacity			10.6 gal.
Fuel Requirement		87 octane regular unleaded gasoline
Tires				P195/65 R15 89S Goodyear Assurance
Brakes, front/rear		vented disc / solid disc,
				 ABS and regenerative braking standard
Suspension, front/rear		independent MacPherson strut/
				  semi-independent torsion beam axle

EPA Fuel Economy - miles per gallon
    hybrid MPG / MPGe / observed		50 / 95 / 53
0 to 60 mph					10  sec (est)

Carpet floor and trunk mats			$ 225
Wheel locks					$  67
First aid kit					$  29
Emergency assistance kit			$  70
Destination charge				$ 760