Toyota Prius

The Toyota Prius is one of world's first commercially mass-produced hybrid automobiles. Manufactured by Toyota, the Prius first went on sale in Japan in 1997. Since then, there have been over 120,000 units sold in Japan, Europe, and North America as of September 2003. The Prius (2000~2003 model years) is certified as a super ultra low emission vehicle (SULEV) by the California Air Resources Board (CARB). The 2004 model is certified as an Advanced Technology Partial Zero Emission Vehicle (AT-PZEV).

How it works

The Prius has been called a true hybrid vehicle, designed from the bottom up. Toyota's goal for the Prius is to reduce the amount of emissions it produces and to be as energy-efficient as possible. They used several methods to try to achieve this goal, including:

1. More efficient use of the internal combustion engine (ICE) and electric motors, reducing gasoline consumption. The Prius uses the more efficient Atkinson Cycle engine instead of the more common Otto Cycle;
2. Two electric motors, providing 67 hp (50 kW) @ 1200-1540 rpm and 295 lb-ft (111 Nm) torque from 0-1200 rpm. which significantly contribute to performance & economy.
3. Lower coefficient of drag at 0.29 (0.26 for 2004 model), reducing air resistance especially at higher speeds;
4. Lower rolling-resistance tires, reducing road friction;
5. Regenerative braking, a process for recovering kinetic energy when braking or traveling down a slope and storing it as electrical energy in the traction battery (a rechargeable nickel metal hydride (NiMH) battery) for later use while reducing wear and tear on the brake pads;
6. Continuously variable transmission. The Prius does not use a "true" CVT, instead the gear ratios are fixed. One can accelerate from zero to the maximum speed in one gear, however engine torque is not multiplied by the transmission. This lack of low-end torque is made up for by the two electric motors, which are connected to the ICE in a planetary gear arrangement.
7. Flexible resin gas tank, reducing the amount of hydrocarbon emissions in the form of escaped gasoline vapor.

Touted advantages of the Prius over previous energy-efficient designs include never needing to be plugged in, all power being delivered ultimately from the gasoline engine. This means it drives like a traditional ICE automobile, the onboard computer in the Prius taking care of shifting power to and from the engine and motors, automatically determining the most efficient use of the engine or the electric motors (or both) based on driving conditions, and when to charge the battery.

The engine is permitted to shut down once the engine has warmed up and the catalytic converter in the exhaust system has reached operating temperature. Once this occurs, the Prius can be driven on electric power only; this is sometimes referred to as "stealth mode" due to the lack of engine noise. This further reduces gasoline consumption and wear and tear on the engine. When driving conditions demand additional power from the engine, it is designed to start up automatically.

Frequent starting up and shutting down of the engine should not cause additional wear and tear, as in conventional automobiles, because the drive motors have enough power to quickly and smoothly spin the engine to optimal rpm (around 1,000) before the engine actually begins to "fire up". This avoids wear when the engine is "running" (with fuel and spark) at very low RPM, as happens in most vehicles.

The Prius gets better fuel efficiency in the city because the batteries get used more, whereas on the highway, the engine is used in order to recharge the batteries, and the wind resistance is higher.

2004 Prius

The Prius 2004 model year is a complete redesign of the previous generations of Prius. With a new drag coefficient of 0.26 and featuring the third generation hybrid powertrain technology called Hybrid Synergy Drive (HSD) replacing the old Toyota Hybrid System (THS) technology, the new 2004 Prius is a midsize car with more room than the previous subcompact (4 doors plus a rear hatch, a smaller but higher voltage NiMH battery), is more powerful (2 seconds faster in 0 to 96 km/h acceleration) and is 15% more fuel efficient than the previous generation Prius (59 mpg city, 51 mpg highway, according to the EPA) when driven properly[1] , yet is still 90% cleaner than conventional gasoline-only automobiles. It comes with an Advanced Technology Partial Zero Emission Vehicle (AT-PZEV) certification by CARB. As an interesting side note, a $2,200 option package offered in Japan for the 2004 model gives it the ability to perform parallel parking by the on-board computer. Eighty percent of the Prius buyers in Japan have chosen this option. The system is not intelligent, though, so it is very limited.[2]

Notable facts

• Drivers of the Toyota Prius, or other Hybrid-Engine automobiles are allowed to drive by themselves in Carpool (High Occupancy Vehicle) lanes in some US states such as Virginia, California (pending) and Florida (requires $5 per year decal).
• Due to the success of both the engineering and sales of the Prius, Toyota is currently planning a hybrid V-6 engine for the Lexus RX400h, as well as a hybrid engine version of the Highlander.
• Toyota is also actively developing a hydrogen-fuel-cell engine. They have already successfully developed a RAV4 that can achieve 900 miles (1450 km) on one tank of hydrogen.
• Starting with the 2004 model, Toyota is now producing the Prius on a standard mass production assembly line, resulting in one being produced every minute instead of one every 8 to 10 minutes. The use of a standard assembly line has dropped the price significantly, which in turn has generated publicity and popularity.
• Toyota is considering opening a US assembly line for the Prius in 2005.
• The fuel tank holds 11.9 gallons (45 L), giving a range of up to 600 miles (1,000 km).
• In June 2004, the Wall Street Journal reported that the backlog for 2004 Prius has reached 22,000 in the US.
• As of April 2004, the expected delivery time for Prius in the Netherlands is one year.
• As of March 2004, the waiting list in Sebastopol, California was over 100 people long.
• As of February 16, 2004, Toyota USA is not taking new internet orders for the 2004 Prius.
• As of December 14, 2003, the waiting time in Dallas, Texas, USA, was 6 months.
• The battery pack of the 2004 Prius is guaranteed for 100,000 miles (160,000 km) or 8 years. The warranty is extended to 150,000 miles (240,000 km) or 10 years for Prius in California and several other states that adopted the Californian emission control standards.

Other hybrid-engine vehicles

• Honda Civic Hybrid, another car which works similarly, but never runs exclusivley on electricity.
• Honda Insight, a 2 seater hybrid car which the EPA claims gets 60 miles per US gallon in the city, 66 mpg highway (3.92 litres per 100 km city, 3.56 L/100km highway ), also cannot be driven without the gasoline engine.
• Ford Motor Company is planning a hybrid engine version of the Ford Escape. Ford signed a licensed agreement in March 2004 to use 20 hybrid technology patents from Toyota.

See also

• Toyota
• Hybrid car

External links

• Official Prius web site
• Toyota's paper on how the 2004 Prius is different from earlier models (in PDF)
• A detailed discussion on all, including technical aspects of Prius at Graham's web site
• A lot of very valuable information, tips, and photos about Prius at John's web site
• Search for keyword "Prius" on Yahoo! Groups
• California Air Resources Board
• MSN Autos listing for the 2004 Prius
• Automotive Industries article, many details