Driving the Toyota Prius Plug-in Hybrid Vehicle – A Better Prius!

Posted by John Dolan | Posted in Community, Hybrids, News, Uncategorized | Posted on 22-10-2012

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When you get behind the wheel of the new Toyota Prius Plug-in Hybrid (PHV) — indeed before that — the car seems very familiar.  With so many Prius models traversing our roadways these days that should not come as a surprise.  The hybrid icon is the most popular vehicle in a growing automotive segment: over half of every hybrid sold is a Prius.  This broad appeal makes the Prius an ideal platform to refine and improve Toyota’s hybrid technology.  It’s also reassuring to know that the Prius Plug-in has the reliability and dependability of Toyota Hybrid Synergy Drive engineering behind it. Since the car company has well over a decade’s worth of experience figuring out how to sell a simple-to-use hybrid car to the masses, it is pretty obvious the engineers and marketers at Toyota realize these things, too!

Inside it is pretty much all standard Prius, complete with the futuristic dashboard, plenty of space and the familiar little drive selector protruding from the familiar flying-buttress raised center-console.  The driver-selectable mode switches are there too.  However, the EV mode is now a combination HV/EV switch which enables greater control over vehicle performance and efficiency.

Powering up the car, which is the same push-button experience that Prius drivers are used to, calls up a new multi-information screen, but results in very little sound — also familiar.  At start-up the car automatically defaults to EV (Electric Vehicle) mode.  The main difference here is that on the move the car isn’t so intent on getting out of EV mode as the regular Prius.  The car accelerates with reasonable power and driving up to 62 mph without the engine kicking in is a pleasant driving experience.  This experience alone is enough for many of us to figure out that this Prius is yet another step down an evolutionary timeline towards the Prius we’ve always wanted!

The new HV/EV mode extends this ability and is designed for city drivers who do not want to frustrate traffic, as in the standard Prius when they would resolutely creep away from the stop light trying to keep it in electric drive.  The HV/EV switch allows the driver to select between HV (Hybrid Vehicle) mode — which behaves like a regular Prius and EV (Electric Vehicle) mode.  An advantage of this would be when one was say, heading out on a longer highway trip.  The driver could select HV mode and the vehicle would perform like a standard 50 mpg-plus Prius on the highway.  Once the driver returned to stop-and-go city driving — they could then switch over to EV mode and the Prius Plug-in reverts back to electric-only driving. Smart, isn’t it? It’s just like a regular Prius — only better.  Driving in EV mode it is easy to think this switch makes your Prius PHV operate like an electric car, but crush the gas pedal and you’ll be quickly reminded that it is still a Prius — close to electric at times, but not quite!  

As you ease away from the curb and briskly accelerate, the most noticeable difference between the standard Prius and Plug-in model is how a hybrid-adept right foot can move the PHV forward into traffic and maintain speeds of up to 62 mph using electricity alone. The PHV’s electric/gas threshold is slightly higher than the regular car’s, but apply anything more than steady pressure on the go pedal — as might be required to enter the freeway or accelerate up a hill — and the 98-hp, 1.8-liter four-cylinder begins to stir to life.  Forget that it is after all, a regular Prius and press the pedal aggressively and the PHV will fire up its internal-combustion engine if you’re not careful.  In true-to-Prius form you can easily engage the gas engine at speeds well below that threshold if you punch the go pedal. Any sudden throttle input will force the combustion engine to burn some of your precious petroleum. If you’re cruising on the highway at say, 60 mph and let your speed dip to 55 and then nudge it back up to 60, you can do so on battery power. But, if you try to go from 55 to 60 more quickly (in a passing situation, for example), you will certainly start to burn gas.  Maintain a judicious, somewhat geezerly driving-style though, i.e., drive the speed limit, and a Prius PHV with a full charge can travel up to 15 miles in electric mode, which becomes considerably more pleasurable the faster one travels.  Once the battery pack is depleted, the car reverts to the conventional hybrid 50 mpg behavior of the standard Prius.

Even under full throttle, the PHV behaves like a standard Prius though a tad slower with a 0-to-60-mph time.  Blame the heavier battery pack and its ancillary hardware—which add about 330 pounds to the car — for the  slightly slower time.  But then, the Prius never has been and never will be, about driving celerity; it is more about maximum fuel economy. At the end of the drive there is PHV vindication — the driving experience is not about getting to the next stop light faster, but rather the numbers that are neatly displayed on the dashboard. Over an average week of driving it is entirely possible by utilizing multiple charging cycles, to move about the city and short highway loops powered solely by electricity much of the time.

Station[1]Every Prius Plug-in comes equipped with heated front seats, even those with fabric upholstery.  The seat heaters come in handy on those cooler days and for short trips because the heaters give you the option to not use the car’s heater.  Reduced heater (and defroster) use will have fuel economy benefits for those of us who dwell in the colder, northern climes, since the role of EV (electric vehicle drive) is diminished once the snow begins to fly.  In all practicality, this is because heater and defroster use will turn on the internal combustion engine (ICE) to supply warm coolant to the vehicle’s heater core.  This is a given. When this happens, the Prius PHV is not in EV because the engine is running, but the hybrid system is still getting more electricity from the battery-pack than it would in HV mode.  The Prius with a plug is designed to take advantage of this since the engine needs to run to supply heat during the winter anyway.  Consequently, you will not get as many pure EV miles during the colder months, but you will still get outstanding fuel economy.  Since diminished fuel economy over the winter months in the upper Midwest is a given in any vehicle, including the standard Prius, loss of EV range in cold months is to be expected.  On the positive side, hybrid system warm-up in the PHV is faster than with the regular Prius.  Also, the battery-pack can be pre-heated simply by timing your vehicle recharging to conclude close to your departure time.  Having more electricity and more motor power available will deliver a nice improvement to winter efficiency.

Just as it is behind the wheel, an obvious take-away from looking over the Plug-in’s exterior is familiarity.  The Prius PHV looks, feels and drives pretty much like the standard version of the world’s most popular hybrid.  The Plug-in does receive some important advances – ones that hardcore Prius chat-room fans will notice right away — but it’s more than obvious that Toyota’s thinking with the design of the Plug-in is evolution, not radical change.Although the changes start with the PHV’s new lithium-ion battery pack, the most noticeable changes are on the outside.  The body work is essentially that of a familiar Prius liftback, but there are subtle detail changes like an extra ‘filler cap door’ concealing the charge port.  Other detail garnishments include matte-silver door handles, front bumper and rear hatch trim with blue-tinted headlamps and 15-inch alloy wheels.

Trunk space hasn’t suffered despite the larger battery.  It is still a Prius in the cargo area, too. But one with a more potent 4.4 KWh lithium-ion battery instead of the standard 1.3 KWh nickel-metal hydride battery pack.  The specs of the hybrid system are the same as the standard Prius — combining a 98hp Atkinson-cycle gas engine with a 80hp synchronous AC electric motor with a total system output of 134hp.

The larger lithium-ion battery pack is modular in design and consists of three modules – with the middle module charging up via the inverter and the two outside modules getting their charge from an outside source.  Though much smaller than the packs used in the two of the other plug-in vehicles on the market, the Prius Plug-in’s 176-pound, 4.4-kWh battery pack is, according to Toyota, “a balance of cost, capacity and weight” and offers just enough juice for an “electric-only driving range of up to 15 miles at a maximum speed of 62 mile- per-hour”.
After you charge it up — which takes just two-and-a-half to three hours from a standard 110-volt outlet (or around 90 minutes with one of the 27 or so Level 2 chargers that are strategically placed around Madison, Wisconsin where we live) you can muster 12 to 15 miles of city driving without any emissions.  By driving with the typical Prius ‘pulse and glide’ technique it is possible under some driving conditions (undulating terrain, not too hilly) to easily attain the 15 mile range.  This is because the battery pack does receive a small amount of charge via the inverter and through regenerative braking.  Incidentally, the Prius Plug-in comes with a 24-foot all-weather charge cord that stows conveniently in a recess below the cargo hold floor.

From the driver’s seat, the Prius PHV is like any Prius in that it surrounds you with information. Only more of it! A heads-up information (HUD) display is available on the Advanced trim level, and Toyota has also re-designed some of the information you can get from the info screen on both trim levels. For example, the new multi-information display in the Prius Plug-in now includes a EV Drive Ratio display that records the ratio of driving distance covered by EV power and the Hybrid System Indicator shows possible EV driving range when in EV mode. There is also a monthly fuel consumption record available, which emphasizes the sort of futuristic, computer-based driving experience that the Prius has always encouraged. Toyota’s Entune info-tainment system — that junction where cell phone and car begin to merge is also standard equipment. Entune provides access to Pandora, iHeartRadio, Bing, Movie Tickets and OpenTable. The Advanced trim level adds Premium HDD Navigation and other plug-in vehicle-specific apps to the standard Entune system such as: Charge Management, Remote Air Conditioning System, Charging Station Map, Vehicle Finder and Eco Dashboard. There is also a way to log-in to XM Stocks — as if you need to check on all this stuff while driving!?

All in all, driving the Prius Plug-in Hybrid conveys the exact same feeling as driving a standard one. When driving is mostly confined to the city, especially when that city is as progressive as Madison, you may not ever have to use gas throughout your urban travels. Most of us would not mind topping the battery off on the move or in our garages at night (utilizing the charge management timer that is standard on the Prius PHV). Prius Plug-in owners do most of their charging, in fact, at home. Minor life-style changes like this are essentially trade-offs — in this case trips to the gas station are exchanged for frequent, mostly at-home, battery charging. And seeing the gas gauge needle barely move for weeks at a time would not be a bother to anyone! With the Prius Plug-in it seems that Toyota is targeting buyers who want a better Prius. Not necessarily the enthusiastic early adopters who have the wherewithal to pay out bigger dollars for a Tesla Roadster or a Volt, or those who desire the all-electric purity of the Leaf. Because that’s really what the Prius Plug-in Hybrid is — a better Prius.

Now let’s compare the Prius PHV to other cars with a cord: The all-electric Nissan Leaf has an official range of 73 miles from its 24-kWh pack and the Chevrolet Volt is rated at 35 miles on a full charge of its 16-kWh pack before the range-extending gas engine kicks in. In the interest of self-preservation, none of these plug-ins use all of the energy capacity that their batteries can hold.  Prius PHV covers 29% of the miles on electricity with 4.4 kWh battery. Volt covers 64% with 16 kWh battery. Which plugin makes the best use of battery? The Prius PHV covers 71% with a 50 MPG gas engine. Volt covers 36% with a 37 MPG gas engine. Which plugin makes the best of gas? It takes 10 hours to fully charge Volt with the bundled charger. It takes Prius PHV 3 hours. Gas, of course, refuels in minutes. Which plugin takes longer to refuel?

The EPA bestowed the Prius Plug-in with a fuel economy rating of 95 mpg equivalent and a rating of 50 mpg when operating only on gasoline (same as the standard Prius). Compare this to the Volt, which gets just 37 mpg combined (using premium fuel) when the battery runs out (after many more EV miles, granted!).

 

Even though the Prius Plug-in Hybrid’s pack is small compared to other plug-ins, it is clearly light years more sophisticated than the standard Prius’ 1.3-kWh nickel-metal hydride pack.  It is the battery pack that allows for a significant increase of electric-only range in stop and go city driving — the type of driving that is the hardest on fuel economy. Of all the changes to the Prius PHV, this is the one that is the most important from an evolutionary standpoint. Whether operating on battery or gasoline, the Prius Plug-in drives and handles almost exactly like the familiar, standard Prius. The only difference — gas goes in on the left side and electricity goes in on the right side!

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