Herb Chambers Tech Snapshot Features Prius Doe

1. An introduction by the U.S. Department of Energy to commercially available advanced vehicle technologies
OFFICE
AND
OF ENERGY EFFICIENCY
RENEWABLE ENERGY
featuring the Toyota Prius
What’s
Inside...
What Is a Hybrid
Electric Vehicle?
Why the Prius?
How Does the
Prius Compare with
Conventional Vehicles?

2. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius
Welcome to the Clean Cities
Advanced Vehicle Information Series
Dear Reader, What Is a Hybrid Electric Vehicle?
A hybrid is any vehicle that uses two or more sources of
Twenty-first century transportation is not just
power — in today’s HEVs, the two sources are electricity
a vision for the future — it’s here today. Clean,
fuel-efficient hybrid electric vehicles (HEVs) (from batteries) and mechanical power (from a small
are now available, joining the alternative fuel internal combustion engine). HEVs can offer the very low
vehicles already on the road. You may have seen emissions of electric vehicles with the power and range of
HEVs in the news, at your local dealership, and gasoline vehicles. They also offer up to 30 more miles per
even in your neighborhood. This brochure is the gallon, perform as well as or better than, and are just as safe
first of the U.S. Department of Energy’s (DOE’s) as any comparable gasoline-powered car — and they never
Technology Snapshots, a suite of publications in have to be plugged in for recharging. Widespread use of
the Clean Cities Advanced Vehicle Information HEVs would help reduce our nation’s growing dependence
Series that is designed to introduce the latest on foreign oil and cut greenhouse gas emissions by one-third
commercially available vehicle technologies to to one-half.
consumers across the country. Each Snapshot
features a different vehicle and offers an objec-
tive, “plain English” explanation of how it works How Do HEVs Work?
and how it differs from conventional vehicles. Hybrids can offer tremendous fuel economy and emissions
The web sites listed on the back cover of this benefits because they operate differently than conventional
brochure provide additional information about gasoline-fueled vehicles.
advanced transportation technology programs.
Gasoline Vehicle: The heat energy obtained by burning
Although nothing can compare to sitting behind
gasoline powers the engine, which drives the transmission
the wheel, each Snapshot gives you a feel for the
that turns the wheels.
featured vehicle by highlighting performance,
vehicle safety, and the benefits the new tech- Electric Vehicle: A set of batteries provides electricity to a
nology delivers to you and your community. Are motor, which drives the wheels.
you ready to drive a cleaner, “greener” and more
fuel-efficient vehicle? Hybrid Electric Vehicle: Not all hybrids are alike. There are
many ways to combine the engine, motor/generator, and
battery. Three basic hybrid configurations are the series,
parallel, and split (or through-the-road) designs.
Thomas J. Gross Series. The engine never directly powers the car. Instead,
Deputy Assistant Secretary the engine drives the generator, and the generator can
for Transportation Technologies either charge the batteries or power an electric motor that
Energy Efficiency and Renewable Energy drives the wheels.
U.S. Department of Energy
Parallel. The engine connects to the transmission, as do
the batteries and the electric motor. So both the engine
and the generator/motor can supply power to the wheels,
switching back and forth as driving conditions vary.
Split. The engine drives one axle and the electric motor
drives the other. There is no connection between the
engine and the electric components except “through
the road.”
2

3. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius
Introducing the Toyota Prius
A New Type of Car… …That Drives Like Any
Toyota’s Prius combines features of Other Car…
both a “series” and “parallel” hybrid The Prius means more than just
electric vehicle, and it is the world’s impressive fuel economy and lower
first mass-produced HEV. The Prius emissions. It is a real car that does
HEVs Ñ Out of the Lab
is a breakthrough in many ways, not have to be “plugged in” or fed and onto the Road
combining an efficient gasoline- expensive or hard-to-find fuels. It
fueled internal combustion engine drives and accelerates like other What started out as a short-term solu-
with a clean, quiet electric motor gasoline-powered vehicles, and tion to extend the range of electric cars
powered by a battery. Like other it feels like a comfortable five-
HEVs, the Prius has many innovative may turn out to be one of the best
passenger sedan.
features: options for increasing fuel economy and
8Regenerative braking: The motor …Only Better. cutting greenhouse gas emissions on
recovers energy from the brakes Toyota’s claims for the Prius are American roads. When automakers
when they slow down or stop the supported by independent labora- installed an onboard generator powered
vehicle and uses it to recharge tory testing by both DOE and
the battery. by an internal combustion engine in an
the U.S. Environmental Protection
electric car to make the car capable of
8Lighter, smaller engine: To Agency (EPA).
improve efficiency, the Prius longer trips, many viewed it as a tempo-
Hybrids may be the cars that
engine is sized to accommodate convince the American public that rary measure until better batteries were
its average power load, not its advanced technology can be both developed. But HEVs caught on in the
peak load. Most gasoline engines affordable and convenient. The next auto industry and, after 20 years of
are sized for peak power require- few pages offer more details on the
ments, yet most drivers need study, a new generation of hybrids is
technology used in these vehicles
peak power only 1% of the time. and illustrate how HEVs can deliver taking center stage in the quest for
8Better fuel efficiency: The Prius a cleaner, comfortable drive today. cleaner, more efficient cars and trucks.
consumes less fuel than vehicles
powered by gasoline alone —
partly because the engine is
turned off when it’s not needed.
Conventional gasoline engines Engine Power to W The Toyot
a
(THS) (left Hybrid System
heels
run constantly, regardless of )
Power to G of both th combines feature
power requirements. enerator e series a s
systems nd paralle
(d l
The key to escribed opposite).
8Lower emissions: The Prius Generator In Parallel t
electronic he THS is an
ally contro
reduces regulated tailpipe splitter t lled power
ha
Motor from the t directs power
en
emissions by up to 90% and wheels an gine to both the
d the gen
greenhouse gas emissions by Compare erator.
Batteries th
conventio e THS to a
about 50% compared with Tier 2 powertrain
nal gasolin
e engine
Mechanica
standards. Electrical
l Power
few more (below); it has a
Power componen
uses them ts,
more effic but it
8More aerodynamic: The iently.
streamlined Prius exterior (0.29 Rear Whee
Engine l
coefficient of drag) reduces drag
by about 14% compared with Transmiss
io Drive Shaft
n
the typical family sedan. 3

4. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius
Focus on Technology
Prius Engine Helps Recharge THS Transmission Provides The result is a quiet and seamless
system — in fact, the only way
the Battery Seamless Shifting to know what mode the car is
Why doesn’t the Prius ever need The THS transmis- operating in is by checking the
to be plugged in for recharging? sion is not a liquid crystal display (LCD) on
Because the car recharges its conventional the dashboard.
batteries primarily by using its own automatic
gasoline engine, in addition to transmission.
Innovative Battery Holds a
regenerative braking. Some of the There is only
power from the engine is “split off” one gear set, Bigger Charge
and stored in the car’s battery pack. with no clutch, The battery pack in the Prius is a
This “self-charging” system greatly starter, alternator, or torque nickel-metal hydride (NiMH) pack
enhances driving range — to more converter. The system fluidly adjusts that operates at 274 volts. The Prius
than 600 miles on a tank of gas in the operation of the gasoline engine, features a prismatic battery, in
the city. generator, and electric motor to which the positive and negative
match driving conditions. The key plates are stacked rather than rolled
Prius Constantly “Talks” to this system is a planetary gear (as in a typical cylindrical battery).
power-split device that allocates The resulting surface area is larger,
to Itself power from the gasoline engine to so the battery delivers more power
The Prius has an electronic control both the final drive and the gener- and is more durable.
system that “talks” to the car’s key ator. The generator produces the
components and ensures that the electrical power that is used to
car always operates in its most recharge the high-voltage battery
efficient mode — for lower fuel pack and to power the electric
consumption and power output that motor. The generator also functions
instantly adjusts to driving condi- as a starter for the gasoline engine
tions. The engine even shuts off — no other starter is needed.
when it isn’t needed for acceleration
or to recharge the battery.
When engine demand is low, such During normal travel, the gasoline
as when starting, traveling at a engine engages as needed to
light load, or stopping, the Prius (1) drive the wheels and/or
is driven only by its electric (2) recharge the battery.
motor, using battery power.
Key: Battery Pack
Inverter
Electric Motor
Engine
4 Generator

5. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius
Inverter Extends Battery Life
An inverter changes the battery’s DC
power into AC power for use by the
Technical Specifications
electric motor, and it also changes Powertrain: Toyota Hybrid System (THS), including: Fuel tank: 11.9 gallons
the generator’s AC power into DC 8Gasoline engine: 1.5-L, 16-valve, 4-cylinder, Max. range: 619 mi (city)/
power to recharge the battery pack. cast-aluminum block and head, EFI Atkinson- 535 mi (highway)**
cycle VVTi (Variable Valve Timing with Passengers: 5
It regulates the power from regener-
intelligence), 13:0:1 compression ratio, 70 hp
ative braking and extends battery at 4,500 rpm, 82 lb-ft of torque at 4,200 rpm Length: 169.6 in.
life by always maintaining the 8Electric motor: Three-phase AC permanent Width: 66.7 in.
proper charge. magnet with peak power of 33 kW/44 hp Height: 57.6 in.
at 1,040–5,600 rpm, peak torque of
350.0 N-m/258 lb/ft (0–400 rpm) Wheelbase: 100.4 in.
Braking System Helps 8Battery: Sealed nickel-metal hydride battery, Weight: 2,765 lb
Improve Fuel Economy 274 volts Cargo: 10 ft3
Transmission: Electronically controlled, Braking: Front disc/rear drum (hydraulic
When a driver slows down or steps on continuously variable, with power assist) with integrated
the brake in the Prius, the regenerative power-split transaxle regenerative system, ABS
braking system converts kinetic energy Max. speed: 100 mph Steering: Rack and pinion, with power assist
from the motion of the wheels — Acceleration: 0–60 miles per hour in Turning circle: 31.6 ft
normally dissipated as heat in the 12.7 seconds
brakes — into electric current to help
Suspension: Front: MacPherson strut
Fuel efficiency: 52 mpg city/45 mpg highway* Rear: torsion beam
recharge the battery. About 20% of Coefficient of drag: 0.29 (drag for 5-passenger car
the total energy consumed by the is typically 0.355) * EPA label values
Prius comes from regenerative Emissions: Meets California Super Ultra ** Based on 11.9-gal fuel tank and 52 mpg city/
braking, which contributes to the Low Emissions Vehicle (SULEV) 45 mpg highway.
car’s excellent fuel economy. standards
At full acceleration, the battery When decelerating or braking, the The engine shuts off when the car is
adds its power to the mix, which regenerative braking system acts idling or if engine demand is low. The
provides a very smooth and as a generator to help recharge gasoline engine runs only as needed to
powerful response. the battery. recharge the battery or run the air
conditioner, which is why the Prius never
has to be plugged in for recharging.
5

6. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius
Independently Tested by the DOE and EPA
DOE Focuses on Argonne researchers focused
primarily on the powertrain control
Prius Performance and energy management systems,
Starting in March 1999, DOE measuring numerous system func-
conducted independent testing tions: engine speed and mass airflow;
of the Prius at Argonne National exhaust gas and coolant temperature;
Laboratory and the National generator and motor speeds;
Renewable Energy Laboratory accumulated ampere-hours; battery
(NREL). The testing goals included voltage; battery, motor, and gener-
determining the operating ator current; vehicle speed; carbon
performance of the hybrid monoxide (CO), nitrogen oxides
technology and collecting data (NOx), and hydrocarbon (HC)
to determine the overall energy emissions; and fuel efficiency.
management performance of the NREL researchers focused on battery
entire vehicle and its individual thermal management performance.
components, including the batteries.
Work at DOE laboratories included devel-
oping an engine map — the set of data
that relates an engine’s fuel consump-
tion, power output, and emissions;
examining the vehicle’s hybrid control
strategy; collecting data on powertrain
EPA Takes a Closeup operation; outfitting a car for mobile
testing during on-road city and highway
Look at THS driving; and extensive battery testing.
In 1998, the U.S. Environmental Protection
Agency evaluated the Prius THS technology Why Drive a Hybrid Air Emissions
over two test sequences involving the Growing scientific evidence suggests
Federal Urban Dynamometer Driving
Electric Vehicle?
that greenhouse gas emissions
Schedule and the Highway Fuel Economy As the information in this brochure illustrates, the Prius
could contribute to a change in the
Test (HFET). and other HEVs are mechanically innovative, sophisticated
earth's climate — and transpor-
vehicles. Many people might ask why they should drive
The results of these tests are provided in tation, specifically the combustion
these technological marvels when their current car does
the EPA report “Evaluation of a Toyota of fossil fuels in our vehicles,
everything they want it to do. The two best reasons are
Prius Hybrid System,” EPA420-R-98-006, accounts for a large portion of
(1) to improve mileage and (2) to reduce emissions.
greenhouse gases. Moreover, EPA
August 1998, on the EPA website:
The Outlook on Oil considers a number of other pollu-
www.epa.gov
tants in vehicle emissions to be
Most people dislike having to pay $20 or $30 or more for
harmful to public health and the
a tank of gas. Yet, the United States depends on petroleum
environment. Despite the substan-
for nearly 95% of its transportation energy — about 8
tial reductions in individual vehicle
million barrels per day of petroleum products are used to
emissions over the last few decades,
fuel light trucks and cars. More than half of our petroleum
the millions of vehicles on our
is imported, and this percentage is growing, which is why
roads — which burn thousands
oil imports represent one of the largest components of the
of gallons of petroleum every
U.S. trade deficit. And the demand for oil used for trans-
second — account for a third of
portation will grow as the number of people and the
the country's air emissions.
number of miles they drive increase.
6

7. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius
Fuel Economy Emissions Comparison
New Car Requirements
Prius (Actual 2000
Prius 46.0 EPA Test Results) 0.009
SULEV (California's
Most Stringent Light-
Corolla 31.6 Duty Vehicle Standard 0.02
Starting 2004)
TIER 2 (Federal
Light-Duty Fleet
Camry 25.3 Average Standard
0.07
Starting 2004)
20 25 30 35 40 45 50 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
Fuel Economy (miles per gallon) Oxides of Nitrogen (NOx) (grams/mile)
Acceleration (0–60 mph) Handling (Slalom)
Prius 12.7 Prius 11.5
Corolla 11.4 Corolla 12.1
Camry 12.2 Camry 11.5
9 10 11 12 13 11.0 11.2 11.4 11.6 11.8 12.0 12.2
Time (seconds) Time (seconds)
Picture-Perfect Performance The Prius truly appeals to people who want a car with excellent performance
that is also friendly to the environment. The "Emissions Comparison" chart above
DOE took its testing efforts on the road in illustrates how Prius almost eliminates harmful emissions — it already meets
September 2000. At the Route 66 Motor California Super Ultra Low Emission Vehicle (SULEV) standards that take effect
in 2004 — without sacrificing performance (see table below). Prius reduces
Speedway near Chicago, Argonne engi- hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxides (NOx) emissions
neers tested the model year 2001 Prius by up to 90% and carbon dioxide (CO2) and other GHG emissions by up to 50%
against a similarly equipped 2001 Toyota relative to those of a comparable gasoline-fueled vehicle. But the vehicle can still
handle as well as or better than comparable 5-passenger cars (see slalom and
Camry and 2001 Corolla to see how they
skid pad test results below), accelerate from 0 to 60 mph in under 13 seconds,
compared in terms of fuel economy, accel- and achieve fuel economy as high as 52 miles per gallon.
eration, handling, and braking. The results
are shown in the charts above and in the Prius Corolla LE Camry LE
table at right.
On-Road Fuel
Economy (mpg) 46.0 31.6 25.3
EPA Fuel Economy
(city/highway) (mpg) 52/45 29/33 23/32
Acceleration (sec)
0–60 mph 12.69 11.41 12.15
Slalom (sec) 11.45 12.10 11.46
Skid Pad (G) 0.654 0.667 0.651
Braking (ft from
60–0 mph) 135.1 173.6 * 198.2
Passenger/Luggage
Volume (ft3) 89/12 88/12 97/14
*Not equipped with anti-lock brakes. 7

8. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius
The U.S. Department of Energy’s mission is to enhance our
nation’s energy security, national security, and environmental
quality, and to contribute to a better quality of life for all Americans.
The widespread availability and use of alternative fuels and clean,
energy-efficient, advanced technology vehicles (like those profiled in the Technology Snap-
shots) will help reduce U.S. dependence on foreign petroleum and promote clean air and
healthier living in communities nationwide.
Prius Cleans Up Related Web Sites
with 5 Environmental http://www.ott.doe.gov/
The U.S. Department of Energy’s Office of Transportation Technologies
Awards (OTT) develops and promotes advanced transportation and alternative
fuel vehicles and technologies.
8United Nations Environmental
Protection Award http://www.ccities.doe.gov/
OTT’s Clean Cities Program supports the deployment of alternative fuel
8EPA’s First Annual Global Climate vehicles and supporting infrastructure.
Protection Award http://www.ott.doe.gov/hev/
8Sierra Club’s “Excellence in OTT’s Hybrid Electric Vehicle Program.
Environmental Engineering Award” http://www.eren.doe.gov/EE/transportation_related.html
Related sites from government, educational, commercial, and
8”Clean Car Salute” from the Clean Car organizational sources.
Coalition, a group composed of state,
http://www.toyota.com
regional, and national environmental Toyota Motor Corporation web site.
organizations in the U.S.
http://www.fueleconomy.gov
8Exhibited at the Museum of Modern The web-based version of the DOE/EPA Fuel Economy Guide.
Art, “Different Roads: Automobiles
for the Next Century”
This document highlights work sponsored by agencies of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes
any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or
process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade
name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any
agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof.
8 Publishing services provided by Argonne National Laboratory