Toyota Prius information and specifications (every generation)

The Toyota Prius was the world's first mass-produced hybrid gas-electric vehicle. The electronic controls that make up the Toyota Hybrid System (THS) allow Prius to run on electricity, gasoline, or a combination of both. The ratio of power provided by each system is constantly monitored, depending on speed and load, to keep the vehicle in its most efficient operating mode.

The Japanese version managed 66 mpg, but it was designed for low-speed driving areas. The US version was changed to match the higher speeds and greater proportion of highway driving, as well as to reduce emissions and comply with California's Super Ultra Low Emission standard (SULEV) - 85% cleaner than the ULEV standard.

How the system works

The five main modes are:

1. When pulling away from a stop or under a light load, only the electric motor powers the vehicle.

2. In normal driving, power from the gasoline engine is divided by a power-split device between the wheels and the electric generator. The generator runs the electric motor to provide additional power to the wheels.

3. Under full-throttle acceleration, the electric motor is supplemented by power from the batteries.

4. During deceleration or braking, the motor functions as a generator to recharge the batteries. The batteries never need to be recharged from an external source. The gasoline engine also shuts down, creating zero exhaust emissions and using no fuel.

5. The battery is regulated to maintain a constant charge. When the charge is low, the electric generator routes power to charge the battery.

The key to the system is a power-split transmission, which sends engine power either directly to the wheels or to the electric generator controlling the electric motor or battery state-of-charge. The power-split device uses a planetary gear to constantly vary the amount of power supplied from the engine to either the wheels or the generator. The electronically controlled transmission smoothly adjusts the rates of revolution of the gasoline engine, electric generator and electric motor to accommodate for acceleration and deceleration.

The engine is kept within its most efficient speed and torque range as much as possible to maximize fuel efficiency, as engine speed can be controlled independently of road speed through the planetary gear set. When the engine falls out of this range, such as when the vehicle is pulling away from a stop, descending a slight grade or moving very slowly, fuel is cut off and the engine is stopped. In this mode, initial move-off power is supplied by the electric motor as it produces 100 percent of its maximum torque immediately off of idle. When power requirements change, the engine is instantly and imperceptibly started by the generator and the electric motor is used to supplement acceleration.

To further boost system efficiency, Prius is fitted with a regenerative braking system. When the vehicle is coasting or the brakes are applied, the motor is turned into a generator, capturing energy that would normally be lost as heat or kinetic energy and transforming it into electricity to recharge the batteries. The system is particularly effective during stop-and-go driving. Indeed, without regenerative braking and coasting, the Prius would probably not be much more efficient than a standard gasoline car.

The braking system is a "brake-by-wire" design. When the brake pedal is depressed, a computer sends a signal to the regenerative system to begin to slow the vehicle. If the pedal is pressed further, the standard hydraulic brakes are operated. Front disc brakes are teamed with rear drums, and an anti-lock system (ABS) is standard.

American version specifications

Standard equipment includes ABS brakes, thermostat-controlled air conditioning, power windows, door locks and mirrors, an cassette stereo, an eight-year/100,000-mile battery and hybrid-related component warranty, roadside assistance and three-year basic maintenance programs.

Prius' primary power is provided by an all-aluminum 1.5-liter gasoline engine with a peak 70 horsepower at 4,500 rpm and peak torque of 82 lb./ft. at 4,200 rpm. Variable valve timing maximizes efficiency. The gas tank has a plastic bladder which reduces gasoline vapors.

The American also has a more powerful, more compact, and lighter main battery pack. The pack is 30 percent lighter in weight than the units in the first-generation Prius. The new lighter batteries reduce battery pack volume by 60 percent and allow for more cargo area in the trunk.

The electric drive motor is a permanent-magnet design that requires little maintenance as its internal componentry never wears. It produces its maximum power of 33 kW (44 horsepower) from 1,040-5,600 rpm, and maximum torque of 350 N-m (258 lb./ft.) from 0-400 rpm.

In addition to increased horsepower, the U.S. model Prius is equipped with a Toyota
hydrocarbon (HC) absorber and catalyst (HCAC) system for reduced exhaust emissions.
The engine can only rev to 4,000 rpm, so that the internal parts can be smaller and lighter, and to reduce friction loss.

Base MSRP: $19,995

EPA fuel economy: 52 city, 45 highway (that is not a misprint)

SULEV certification

Gas engine: Inline 4-cylinder DOHC, Displacement: 1,497 cc, Compression Ratio: 13.0:1
Peak Horsepower: 70 hp at 4,500 rpm
Peak Torque: 82 lb.-ft. at 4,200 rpm
Fuel Tank Capacity: 11.9 Gal.

ELECTRIC MOTOR - Permanent Magnet, Capacity: 6.5 amperes
Peak Torque: 258 lb./ft. (350.0 Nm) 0-400 rpm

Peak Horsepower: 25 kW (34 hp)
Nominal Voltage: 274 volts

Length: 169.6 in.
Width: 66.7 in.
Height: 57.6 in.
Wheelbase: 100.4 in.
Weight 2,765 lb.
Seating Capacity: 5

Headroom (front/rear): 38.8 / 37.1 in.
Legroom (front/rear): 41.2 / 35.4 in.
Shoulder room (front/rear): 52.8 / 52.2 in.
Hip room (front/rear): 50.7 / 51.9 in.
Passenger volume: 88.6 cu. ft.
Cargo volume: 11.8 cu. ft.
Total interior volume: 100.4 cu. ft.
EPA class: Compact

Transmission: Electrically Controlled CVT

Braking: Front ventilated disc/Rear drum (Hydraulic, with Power Assist)
with Integrated Regenerative Brake System

Steering: Rack and Pinion
Suspension (front/rear): MacPherson strut / Torsion beam

Japanese version specifications

Primary power comes from a 1.5 liter gas engine, which produces 58 horsepower in the Japanese version (75 lb-ft of torque). It has variable valve timing. The American version has more power. The engine can only rev to 4,000 rpm, so that the internal parts can be smaller and lighter, and to reduce friction loss.

The electric motor is a permanent-magnet design that requires no maintenance as its no-touch internal componentry never wears. It produces its maximum power of 30 kilowatts (40 horsepower) from 940-2,000 rpm, and maximum torque of 31.1 kg-m (225 lb./ft.) from 0-940 rpm.

Length: 168.3 in.
Width: 66.7 in.
Height: 58.7 in.
Wheelbase: 100.4 in.
Weight 2,728 lb.
Seating Capacity: 5

Gasoline Engine: Inline 4-cylinder DOHC, 1,496 cc.
Compression Ratio: 13.5:1 - (HP): 58/4,000 rpm - (Torque): 75 lb./ft./4,000 rpm
Fuel Tank Cap.: 13.2 Gal.

Electric Motor: Permanent Magnet
Max. Power: 30kW/40 horsepower (940-2,000 rpm)
Max. Torque: 31.1 kg-m/225 lb./ft. (0-940 rpm)

Braking: Front Disc/Rear Drum (Hydraulic, with Power Assist) with Integrated Regenerative System

Steering: Rack and Pinion
Suspension: F: Independent MacPherson Strut R: H-beam
Battery: 40 7.2-Volt Sealed Nickel-Metal Hydride - 6.5 Ah/3 HR capacity

Bill Powell noted: The 1998 Japan home model used round cells, and had a known problem with charging and supplying power: one of the reasons for the switch to prismatic. The prismatic "upgrade" involves a new HV battery pack and associated ECU as well as a replacement hybrid system ECU. It is NOT plug-and-play by any means. Those poor sods that have decided to use Japanese Prius elsewhere are in deep doo-doo since they will find NO support and minimal hope of ordering parts even if there is an in-country Toyota establishment...

Toyota Prius review

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