The Toyota Prius is a hybrid electric vehicle developed and manufactured by the Toyota Motor Corporation. The Prius first went on sale in Japan in 1997, making it the first mass-produced hybrid vehicle, and was introduced worldwide in 2001. The Prius has also won several awards.
According to the United States Environmental Protection Agency, the 2008 Prius is the most fuel efficient car sold in the U.S.,[4] and, according to the UK Department for Transport, the Prius is tied with the diesel MINI Cooper D as the second least CO2-emitting vehicle behind the Volkswagen Polo 1.4 TDI.
History
In 1994, Toyota executive Takeshi Uchiyamada was given the task of creating a new car which would be both fuel efficient and environmentally friendly. The engineering team quickly settled on a hybrid engine design, but many technical and engineering problems had to be solved within the three years that the team was given to bring the car to the Japanese market, a goal they barely achieved as the first Prius went on sale in December 1997. A main problem was the longevity of the battery, which needed to be between 7 to 10 years. The solution the engineers came up with was to keep the battery pack between 60% and 40% charged, proving to be the "sweet spot" for extending the battery life to roughly that of the other car components.
The car was a modest success in Japan and after gathering several years of test data from the Japanese early adopters, the company felt it was safe to put it on sale in the U.S. market. Sales were small at first (though the waiting list was six months for the first few years in the U.S.) but picked up substantially in 2004. The Prius is considered to be a successful car for Toyota from both technical and marketing perspectives. Whether the car has actually generated any net profit for the company is unknown, but, according to the head of the Prius team, the company initially lost money on the Prius.
The word prius is a Latin word meaning "to go before". A Toyota spokesman stated that "Toyota chose this name because the Prius vehicle is the predecessor of cars to come."
Design
Technology
The Prius is a parallel hybrid, a vehicle that can run on gasoline and/or electric power. Components of the system include:
- A 1NZ-FXE ICE using the more efficient Atkinson cycle instead of the more common Otto cycle;
- Two electric motor/generators: MG1 and MG2. MG1, with -10,000 to +10,000 RMP, starts the engine and provides counter torque for the CVT. MG2 provides 50 kW (67 hp) between 1,200 to 1,540 rpm and 400 N·m (295 ft·lbf) torque between 0 to 1,200 rpm, contributing to performance and economy;
- A drag coefficient of 0.26 (0.29 for 2000 model) with a Kammback design to reduce air resistance;
- Lower rolling-resistance tires to reduceroad friction;
- Regenerative braking, which converts kinetic energy into electrical energy that is stored in the traction battery and reduces wear and tear on the brake pads;
- A Sealed 168-cell nickel metal hydride (NiMH) battery providing 201.6 volts; supplied by Panasonic
- A planetary gearset that behaves like a Continuously Variable Transmission called the Power Split Device to increase efficiency;
- A flexible resin gasoline tank to reduce the amount of hydrocarbon emissions in the form of escaped gasoline vapor (US market);
- A Vacuum flask for storing hot coolant when the vehicle is powered off for reuse so as to reduce warm-up time (US market);
- An EV mode (or Stealth Mode) that allows drivers to operate on electric power only under low-power conditions for a limited duration of time (Europe and Asian markets, aftermarket in the US). Advocates for the blind warn that the Prius is so quiet it could be hazardous to blind pedestrians and others accustomed to engine noise to warn of a nearby vehicle;
- The use of aluminum instead of steel for the engine bay hood for weight reduction;
THS inverter unit (from NHW11)
The HSD in the Prius shuts off the engine when idle, reversing, and descending long hills, therefore decreasing fuel consumption dramatically. The HSD's on-board computer determines when and how to use the engine, motor, or both to power the car and recharge the battery so as to maximize efficiency. Typically, a gasoline engine runs inefficiently at half-throttle, creating a choking condition called pumping loss, a major reason for the inefficiency of gasoline engines compared to diesels. The Prius minimises pumping loss by using a high torque range with the throttle fully open. Drive-by-wire throttle control technology and Toyota's Hybrid Synergy Drive (a torque combiner, electric drive, and computer control) are essential to this engine control. In addition to the immediate benefit of reducing fuel consumption and emissions, stopping the combustion engine also improves the performance of the catalytic converter, as the exhaust gases from an idling engine tends to cool the catalysts below their optimal temperature.
Consumption monitor on the 2005 Toyota Prius MFD, displaying fuel consumption for highway driving, in the previous 30 minutes, as well as the average fuel consumption for 59 miles since last gas fill-up.
Energy Monitor on the 2005 Prius Multi-Function Display (MFD), showing energy flow to/from the engine, battery, and from the regenerative braking, as well as battery charge level.
For any car, aerodynamic losses due to drag are much greater on the highway than in low speed city driving. A non-hybrid car nonetheless gets worse fuel consumption in city driving because its engine is far less efficient at low power, such as when idle, and because it must frequently dump its kinetic energy into the brakes during stop-and-go driving. The Prius gets better fuel efficiency in city cycles because the engine can shut down instead of running at low power, and run solely off the battery at low speeds and when stopped. This means the greatest advantages of a hybrid are mainly in city driving, though factors including driving style, air conditioning use, and short trips may offset some of this advantage. The frequent starting and stopping of the engine does not cause additional wear and tear or emission problems because the drive motors have enough power to quickly spin the engine to optimal rpm (around 1,000) before the engine fires up. The hybrid has less of an advantage in higher speed open road driving typical of intercity
Energy screen on the 2003 Prius
driving, yet obtains improved fuel consumption under these circumstances since it can use a smaller and more efficient engine than would otherwise be required (because the battery and electric motor can provide the extra peak power needed for passing and limited hill climbing).
The environmental impact of the car's batteries has been questioned. To encourage battery recycling, dealers are paid a $200 fee for return of the car's batteries.
Fuel consumption
The Prius is marketed as a fuel efficient car. In United States Environmental Protection Agency (EPA) test results must be posted on new vehicle windows in the U.S. and are the only mileage figures that can be advertised. Consumer Reports views the estimate as flawed and issued a revised assessment giving a real-world mileage of 44 mpg for the Prius instead of 60 mpg. EPA testing procedures were revised in 2007. According to the EPA's revised estimates, the combined mileage for the 2008 Prius is 46 miles per gallon,making it the most efficient car of 2008.
Models
| Feature | Model code |
| NHW10 | NHW11 | NHW20 |
| Body style | 4 Door
Sedan | 4 Door
Sedan | 5 Door
Hatchback |
| First sales | 1997 | 2000 | 2003 |
| Battery | Modules | 40 | 38 | 28 |
| Cells per module | 6 | 6 | 6 |
| Total cells | 240 | 228 | 168 |
| Volts per cell | 1.2 | 1.2 | 1.2 |
| Total volts (nominal) | 288 | 273.6 | 201.6 |
| Capacity amp hours | 6.0 | 6.5 | 6.5 |
| Capacity Watt hours | 1728 | 1778.4 | 1310.4 |
| Weight kg | 57 | 50 | 45 |
| Petrol Engine | Power kW | 43 | 52 | 57 |
| Max rpm | 4000 | 4500 | 5000 |
| Electric Motor | Operating Voltage | 288 | 273 | 500 |
| Power kW | 30 | 33 | 50 |
| Combined | Power kW | ? | 73 | 82 |
1997-2000 Prius (model NHW10)
The first Prius, model NHW10, went on sale in December 1997.The car was a compact sedan using a modified Vitz platform and engine. It was sold only in Japan, though they have been imported privately to the United Kingdom, Australia, and New Zealand.
2001-2003 Prius (model NHW11)
The 2001-2003 Prius for the United States market was powered by a 1.5-liter 4 cylinder gasoline engine, a permanent magnet AC electric motor, and a 274-volt nickel-metal hydride (Ni-MH) battery pack. The gasoline engine developed 70 hp and 82 lb-ft of torque. The electric motor generated a maximum of 44 hp and 258 lb-ft of torque. Japanese versions were less powerful.
The engine and motor power was increased over the previous model. Options were limited to a CD player and floor mats. Beginning with the 2002 model year, front side air bags, cruise control, and a navigation system were added as optional equipment. Air conditioning and a continuously variable transmission were standard equipment.Use of the air conditioner required the gasoline engine to be running.
In the United States, it was the first Prius. The Prius was marketed between the smaller Echo and the larger Corolla. The published retail price of the car was US$19,995.The California Air Resources Board (CARB) classified the car as a Super Ultra Low Emission Vehicle (SULEV). European sales began in September 2000.The official launch of the Prius in Australia occurred in 2001 after the Sydney Motor Show.
2004-2007 Prius (model NHW20)
2006 Prius Cut-away in Toyota Showroom in Paris
The Prius is completely redesigned into a mid-size liftback which is between the Corolla and the Camry in size. The new model is 6 inches longer than the previous version. Its more aerodynamic body resulted in a drag coefficient of 0.26.
The new Hybrid Synergy Drive (HSD) uses an all-electric compressor for cooling. Combined with a smaller and lighter NiMH battery, the NHW20 is more powerful and more efficient than the NHW11. Air conditioning is now operated independently of the gasoline engine, an industry first. The car is capable of operating on electric power only for longer periods of time. In the U.S., the battery pack of the 2004 Prius is warranteed for 160,000 km (100,000 miles) or 8 years, although Toyota has stated that they expect it to last 15 years. The warranty is extended to 240,000 km (150,000 miles) or 10 years for Prius in California, and in the seven Northeastern states that have adopted the stricter California emission control standards.
It is classified as a SULEV (Super Ultra Low Emissions Vehicle and is certified by California Air Resources Board as an Advanced Technology Partial Zero Emission Vehicle (AT-PZEV).
NHTSA (United States) crash testing of the 2004 Prius yielded a five star driver and four star passenger rating in the frontal collision test (out of five stars). Side crash results were four out of five stars for both front and rear seats. The car scored four out of five stars in rollover testing.
In 2004, EuroNCAP tested the Prius. It earned the following ratings: Adult Occupant 
Child Occupant
Pedestrian 
.
Among the Prius' options are Toyota's implementation of an Advanced key (the feature can be user-deactivated) and Bluetooth for hands-free calling. Automated parallel and reverse parking is available in Japan and Europe.
Production of the Prius for the China market began in December 2005 by Sichuan FAW Toyota Motor, a joint venture with First Automobile Works.
The 2006 Prius introduced some minor cosmetic changes, along with optional features such as advanced airbags, a rear-view camera, an upgraded audio system (including a line-in port), an updated Navigation DVD with new user interface, and a higher-resolution liquid crystal display.
The 2007 Prius adds advanced and side-curtain airbags standard on all models. A Touring Edition was introduced that includes an elongated larger rear spoiler as well as larger, sharper-pointed 7-spoke 16" alloy wheels with plastic hub cap cover to protect it from scratches when parking against the curb. The Touring Edition also comes with a firmer European style tuned suspension, standard high-intensity-discharge (HID) headlights and integrated (non-HID) fog lights.
Hydrogen Prius
Hydrogen powered Prius cars have been developed. Ten were delivered in November 2007 Vistorka, a consortium of companies in Iceland.
Future of the Prius
Toyota CEO Katsuaki Watanabe said in a February 16, 2007 interview that Toyota was "aiming at reducing, by half, both size and cost of the third-generation hybrid system." However, plans to replace NiMH batteries with lithium-ion batteries have since then been cancelled or delayed. Lithium-ion batteries have a higher energy capacity-to-weight ratio, but cost more, and operate at higher temperatures, raising safety concerns.
It has been mentioned that a future Prius will receive an upgrade of the petrol (gasoline) engine from 1.5 litres to 1.8 litres. A plug-in hybrid version of the Prius will allow for less fuel consumption with a bigger engine.It has also been suggested that a range of different sized models are planned, (referred to by engineers as the Prius A, B and C), rather than a single model. The first of these new models is expected in 2009. This new hybrid may carry the Lexus brand.Toyota spokesman said that future Prius research "...is broad-reaching and being carried out from various angles."
Toyota is road testing prototype plug-in hybrid vehicles (called Toyota Plug-in HV).
Government and corporate incentives
Government incentives
A number of governments have incentives that are intended to encourage hybrid car sales. In Belgium, the national government offers reductions in the purchase price of up to 15% for buying cars that have lower CO2 exhaust.
The national government in Canada offers to those who buy or lease hybrid cars a federal rebate.Some provincial governments also offer incentives such as in British Columbia, Manitob, Quebec, Ontario, and Prince Edward Island.
In the United Kingdom, incentives are mostly parking related. Parking incentives exists in Richmond upon Thames (south west London), Westminster (Central London) for resident parking permits, Winchester (now discontinued), Manchester, and Brighton has similar plans.In London can register for exemption from the £8 daily congestion charge. Some of the incentives in the United Kingdom have been criticized in the press given that non-hybrid cars, some of which have better fuel economy, are not afforded the same incentives.
In the United States, the national government offers a tax credit to purchasers until a certain number of cars has been sold by a manufacturer. This has ranged from US$787 to $3,150. State governments, including Colorado, Connecticut, Illinois are some U.S. states which offer tax incentives. Hybird engine automobiles are exempt from high-occupancy vehicle lane restrictions in some U.S. states.), California (currently until January 1, 2011, Los Angeles and San Jose, California had exempted hybrid cars from paying for street parking.
Corporate Incentives
Several U.S. companies offer employees incentives. Bank of America will reimburse $3000 on the purchase of new hybrid vehicles to full- and part-time associates working more than 20 hours per week. Google, software company Hyperion Solutions, and organic food and drink producer Clif Bar & Co offer employees a $5000 credit toward their purchase of a certain hybrid vehicles including the Prius. Integrated Archive Systems, a Palo Alto IT company, offers a $10,000 subsidy toward the purchase of hybrid vehicles to full-time employees employed more than one year. Clothing companies Timberland and Patagonia, law firm DLA Piper, non-profit American Jewish Committee, software publisher Topics Entertainment, and research firm ABR, Inc. are among companies offering eligible employees significant discounts on certain hybrid vehicles including the Prius.
Travelers Companies, a large insurance company, offers hybrid owners a 10% discount on auto insurance in most states. The Farmers Insurance Group offers a similar discount of up to 10% in most states.
Controversies
Lifetime energy cost
A 2006 study by CNW Marketing Research, Inc. calculated the overall energy cost of a Prius at US$3.25 per mile and a Chevrolet Tahoe SUV at US$2.94 per mile. It concluded that 2005 hybrids cost "significantly more in overall energy costs than conventional Internal Combustion Engine (ICE) vehicles." David Friedman of the Union of Concerned Scientists commented that the study "has been completely contradicted by studies from MIT, Argonne National Laboratory, and Carnegie Mellon's Lifecycle Assessment Group."An article on the Better World Club website investigates the source of the statement "a Hummer is more energy efficient over its lifetime than a Prius", which it characterizes as an urban legend. It suggests that the source may be the CNW "Dust to dust" study, or follow-up articles by James L. Martin or Chris Demorro, and goes on to challenge some of the assumptions made in the study. A critique of the 2007 version of the CNW report by the Pacific Institute concluded that "closer inspection suggests that the report's conclusions rely on faulty methods of analysis, untenable assumptions, selective use and presentation of data, and a complete lack of peer review. Even the most cursory look reveals serious biases and flaws."
Name
Prius is a not a verb but a Latin comparative adjective or adverb, the neuter nominative singular form of the adjective whose corresponding masculine and feminine nominative singular forms are prior, (see also Latin declension#Irregular adverbs and their comparative and superlative forms) with meanings "ahead, in front, leading; previous, earlier, preceding, prior; former; basic;" Some enthusiasts enjoy using Prii as the plural, which would be correct if prius were a regular second declension Latin noun. The actual Latin plural of the adjective is priora ( is slightly in error here). All of these forms are nominative case and there are several other forms for the other cases. As for the plural of Prius in English, Toyota has said that it is simply Prius and also that owners are welcome to use whatever they like.
Political symbolism
The large number of Prius-owning progressive celebrities in 2002 prompted the Washington Post to dub hybrids "Hollywood's latest politically correct status symbol." While conservative "Prius Patriots" were also cited in 2005,the vehicle carries an image as being a car for politically liberal environmentalists. A 2007 San Francisco Chronicle article said "Prius Progressives" were becoming an archetype, quoting conservative U.S. pundit Rush Limbaugh opining that "these liberals think they're ahead of the game on these things, and they're just suckers."
Many conservatives promote use of the Toyota Prius. For example, Jim Road from What Would Jesus Drive? encourages people to drive hybrid cars because of the damage that large SUVs can do to others. Driving an SUV, it is claimed, expressed an attitude not consistent with the teachings of Jesus. One could also say that conservatives that promote fiscal responsibility drive the Prius because of its economic benefits. On the other hand, the car is foreign built by a foreign company, and so this statement seems to conflict with the economic concerns that many Christians and conservatives have, especially since domestic manufacturers such as General Motors and Ford Motor Company now offer hybrid vehicles of their own.
Former CIA chief R. James Woolsey, Jr. drives a Prius because of its low petrol consumption. Woolsey claims that money that pays for imports of petrol help fund terrorism and states hostile to the United States. Ben Oliver writes the following: "By rights, Woolsey ought to drive a big, bad Hummer. Instead, he drives a Prius, and he says that if you live in a country dependent on imported oil, it's your patriotic duty to do the same. His argument is simple: It's a bad thing for transport to depend on oil when the great majority of that oil lies in volatile parts of the world whose governments are hostile to the West. Moreover, he argues that, by making the Middle East so wealthy, we're indirectly subsidizing terror. For Woolsey, the cash register at your local gas station is a collection box for al-Qaeda. 'We're paying for both sides in this war, and that's not a good long-term strategy,' he says. 'I have a bumper sticker on the back of my Prius that reads, "Bin Laden hates this car."'"
Fashion over function
In spite of the efficiency goals of the Prius's shape, in 2004, industry analyst Art Spinella of CNW Marketing Research (CNWMR) said "the Prius was a fashion statement," attributing its success over the Honda Civic Hybrid, which is identical to its non-hybrid versions, to its distinctive styling, which lets "other people know the driver is driving a hybrid vehicle.
In focus groups, Spinella said buyers reported choosing the Prius "because of its unique design, and will candidly admit they expect to receive some acclaim from friends, relatives, co-workers for their concern about the environment and/or fuel efficiency."In April 2006, noting "hybrid-vehicle sales actually have decreased since November, when fuel prices began to rise," and citing Prius sales that "dropped 23 percent over the last year," Spinella generalized that "for most people, hybrids are a fashion statement, not indicative of any real concern."
CNWMR's latest figures, first reported on the front page of the The New York Times in July 2007 found that just 36% of Prius buyers cited fuel economy as a prime motivator, while 57% said their main reason was that "it makes a statement about me." The latter number was under 20% in 2004, according to CNWMR.
Shortly thereafter, Washington Post columnist Robert Samuelson coined the term "Prius politics" to describe the practice of showing off rather than curbing greenhouse gas emissions, extending the concept to all ineffective feel-good measures in the broader battle against global warming.
Contrary to the fashion-over-mileage studies, a widely reported study by CNWMR, first covered in The Chicago Tribune, found considerable fluctuations in hybrid demand dependent on fuel prices. Consumers considering hybrids plummeted from 30% to 12% between late 2005 and late 2006 as fuel prices dropped, and were willing to pay a much lower premium over conventional cars in the absence of a fuel price "scare factor," according to Spinella.
Quietness
The Wall Street Journal reported in February 2007 on concerns that quiet cars like the Prius may pose a safety risk to those who rely on engine noise to sense the presence or location of moving vehicles. Blind pedestrians are a primary concern, and the National Federation of the Blind advocates audio emitters on hybrid vehicles, but increased risks may also affect sighted pedestrians or bicyclists who are accustomed to audio cues from vehicles. In July 2007, a spokesperson for Toyota said the company is aware of the issue and is studying options.
CO2 claims
In the UK, the Advertising Standards Authority, an independent body charged with policing the rules of the advertising industry, ruled that a television advert for the Toyota Prius should not be broadcast again in the same form, having breached rules concerning misleading advertising. The advert claimed the Prius "emits up to one tonne less CO2 per year," while on-screen text included: "1 tonne of CO2 less than an equivalent family vehicle with a diesel engine. Average calculated on 20,000 km a year." Points of contention were the vehicles chosen for comparison, whether "up to one tonne less" adequately communicated that reductions could be lower, and whether the distance used was appropriate: 20,000 km per year is around a U.S. car's average annual driving distance, while a UK car's is 13,440 km.
Sales
On 2007-06-07 Toyota announced that it had sold 1 million hybrid vehicles globally, and that of those 757,600 were Priuses.
United States
U.S. sales of the Prius began in August 2000. By 2001 sales there totaled 15,556, and by 2002 had reached 20,119. In 2004 sales there were 53,991, and doubled in 2005 to 107,897, about 60% of the world total of 180,000.By 2006-06-07 266,212 Priuses had been sold in the U.S., and accounted for 40% of the hybrid market there in 2006. As of November 2007 Toyota has sold 510,325 Prius in the US since its initial launch in 2000.
Monthly U.S. sales
| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 |
| Jan |
| 1,298 | 1,954 | 1,606 | 2,925 | 5,566 | 7,654 | 8,299 |
| Feb |
| 1,198 | 1,481 | 1,968 | 3,215 | 7,078 | 6,547 | 12,228 |
| Mar |
| 1,378 | 1,763 | 2,532 | 3,778 | 10,236 | 7,922 | 19,156 |
| Apr |
| 872 | 1,834 | 1,457 | 3,684 | 11,345 | 8,234 | 13,056 |
| May |
| 1,126 | 1,648 | 1,233 | 3,962 | 9,461 | 8,103 | 24,009 |
| Jun |
| 1,534 | 1,369 | 1,069 | 4,219 | 9,622 | 9,696 | 17,756 |
| Jul | 841 | 1,037 | 1,411 | 657 | 5,230 | 9,691 | 11,114 | 16,062 |
| Aug | 788 | 1,311 | 1,756 | 299 | 4,393 | 9,850 | 11,177 | 14,055 |
| Sep | 981 | 862 | 1,382 | 112 | 4,309 | 8,193 | 10,492 | 12,494 |
| Oct | 829 | 1,580 | 1,775 | 4,085 | 6,123 | 9,939 | 8,733 | 13,158 |
| Nov | 989 | 1,580 | 1,956 | 5,584 | 5,866 | 7,889 | 8,008 | 16,737 |
| Dec | 1,134 | 1,780 | 1,790 | 4,025 | 6,287 | 9,027 | 17,883 |
|
|
| Total | 5,562 | 15,556 | 20,119 | 24,627 | 53,991 | 107,897 | 115,563 | 167,010 |
| Cum. Total | 5,562 | 21,118 | 41,237 | 65,864 | 119,855 | 227,752 | 343,315 | 510,325 |
Aftermarket products
EV mode
When the vehicle is turned-on with the "start" button, it is ready to drive immediately with the electric motor, while electric pumps warm the engine with previously saved hot engine coolant, before the internal combustion engine is started. The delay between starting the car and starting the internal combustion engine is approximately seven seconds. The Asian and European versions of this vehicle provide a button labeled "EV" that maintains Electric Vehicle mode after start up, under most low-load driving conditions. The North American model does not have the "EV" button, although the "EV" mode is still supported internally by the Prius Hybrid Vehicle management computer. The PRIUS+ Project offers conversion instructions for do-it-yourselfers who wish to enable the button. Toyota has now received government approval to run on public roads for tests. Researchers at the Advanced Power and Energy Program at the University of California, Irvine and the Institute of Transportation Studies at the University of California, Berkeley will begin testing two specially made Priuses and analyze driver behavior, study air quality and energy use. However, electric-only driving range remains limited to around seven miles (eleven kilometers) per charge in all-electric mode at up to 100 kilometers per hour (62 miles per hour). No date has been set and will not be available to the public until a great deal of additional research has been done.
Plug-in
Plug-in hybrids use a larger battery pack that is recharged from external sources in order to further reduce gas/petrol consumption. The batteries in a production PHEV will be built to handle deeper discharge cycles without loss of lifespan such as those in the Toyota RAV4 EV. Operation of the vehicle will be very similar to a normal hybrid, other than the electric operation will be more prevalent. In the case of a Prius PHEV, under high-load situations such as high-speed roads, the gasoline (petrol) engine will operate as before, leaving the car with the same ability to accelerate and use freeways. Current converted Prius also operate in a high speed blended mode which can reduce but not eliminate gasoline/petrol consumption on the freeway. When driving in slower conditions or other light loads, the batteries will be used first in a charge-depleting mode, allowing moderate commutes at low speeds (particularly under 41 mph/65 km/h) to be driven entirely on electricity. Once the batteries have been sufficiently discharged the car will automatically revert back to the charge-sustaining mode of the current stock Prius. Safe lithium-based batteries exist, eliminating all risk of run-away thermal conditions (spontaneously catch fire or explode) as seen in some laptop computer batteries.
Evolving from the button project, The California Cars Initiative (CalCars) converted a Prius in 2004, adding larger batteries and found out how to safely charge the batteries without affecting the hybrid system. Private companies EDrive Systems in the USA and Amberjac Projects in the UK announced plans to sell conversion kits in 2006 (pushed back to 2007).The most recent versions use a new, patented advanced safe-format Lithium Battery from Valence Technology called Saphion. Using the advanced batteries pushes the final price to an estimated $12,000 US. The energy density and far more efficient utilisation of these batteries provide around 20x the available power of the standard NiMH battery pack but at only double the weight. Tests show it capable of achieving >30 miles (50 km) in all electric mode at speeds below 34 mph (55 km/h). The internal combustion engine starts only at higher speeds or when extra acceleration is needed. Fuel economy is improved to 100 mpg–U.S. (2.35 L/100 km / 120.1 mpg–imp) - 500 mpg–U.S. (0.47 L/100 km / 600.5 mpg–imp) depending on driving conditions. City driving may be possible without using the ICE at all, eliminating the use of almost all liquid fuel in exchange for electrical energy.
PriusPlus is a similar project evolving from CalCars, using lead-acid batteries and a do-it-yourself kit. This conversion gives a car that has 100 mpg–U.S. (2.35 L/100 km / 120.1 mpg–imp) under normal driving conditions. All-electric mode can be used for 10-12 miles in street driving. In January 2007 issue of IEEE Spectrum, CalCars lead technical engineer, Ron Gremban, notes that drivers installing the CalCars Prius+ kit shouldn’t expect a 'positive financial payback.' In addition, the kit adds 135 kg to the car's weight, reducing fuel economy over the stock Prius whenever the gasoline engine is used exclusively. The lead-acid battery pack suffers in cold weather, has a limited life of about 400 deep discharges, and must be recharged within a day to maintain this lifespan. The hope is, by the time the batteries need replacing, a better option is on the market at a comparable price.
Hymotion is a Canadian company (recently purchased by A123systems, an advanced battery company) planning on selling a kit incorporating Lithium-Ion batteries with similar characteristics as EDrive Systems. It is currently undergoing fleet testing, and is planned for sale for 2008.
Solar prius
Awards
English to Chinese BETA
English to French
English to German
English to Italian
English to Japanese BETA
English to Korean BETA
English to Russian BETA 
English to Spanish
![[Valid RSS]](valid-rss-rogers.png "Validate my RSS feed")
