Prius%20Primer

1
Prius Primer

• L. David Roper
• Professor Emeritus of Physics
• Virginia Polytechnic Inst. St. Univ.
• roperld_at_vt.edu
• http//arts.bev.net/roperldavid

2
Toyota Prius II 2004-8(21,000 to 30,000)
A serial-parallel (full) hybrid (gasoline
electric) car
http//www.hybridsynergydrive.com/en/top.html
3
Prius 2004-8 Under the Hood
Aluminum hood
Hood brace
Fuse box with jump-start terminals
Inverter Unit
Engine Generator/motor Motor/generator
4 cylinder engine electric motors 6 cylinder
engine performance.
4
Toyota Prius 2004-6
Power button
generator/motor
Energy-Use 7 Display
Motor/generator
Motion selector
Key fob slot
8-feet ladder (not included)
2005 Fastest selling car in the U.S.
201.6-VoltsTraction battery 12-Volts
system-start/accessories battery
5
Prius Cargo Areas
Small-items storage
Cargo cover
3 3 by 5 9 long
Back seats down
Pull up extra space cover to make room for large
suitcases. False spare tire tools are under
storage bin. Remove storage bin to get to 12V
system-start/accessories battery on right side .
6
Prius Cargo Area
Maps bottle holder (both sides)
Split back seat
Traction Battery
Battery safety plug
Front tow hook.
False spare tire jack
Cargo box tire tools
Small storage bin
12-Volts system-start/accessories battery
7
Toyota Prius 2004-6
Also, audio.
Smart Entry
Motion selector
To start hybrid system, depress brake pedal
before pressing Power once.
Smart Start option fob can be anywhere in the
car.
8
7 Multi-Display

• Can be turned off (Display/Screen off)
• Has daytime and nighttime settings (dark
  background).
• Nighttime settings are in effect when lights are
  on, except when panel dimmer wheel is set to
  maximum.
• Can save settings for different users.
• Outside temperature is shown when energy display
  is active.
• Several display controls are on the steering
  wheel. Holding a button done turns on and off.
• Audio and air conditioning controls can be
  displayed, but some are also available on the
  dash and steering wheel.

9

• http//john1701a.com/prius/presentations/2004-priu
  s_tech-presentation_01.htm

10
Note the flat plates to cut down on drag at high
speeds.
Whats Underneath.
Front of vehicle
Emissions controls
Oil filter
Oil drain
Rear tie down hooks can be replaced by tow bar
for rear bicycle rack.
11
Toyota 2004-8 Prius Specifications

• Engine 1.497 cc, 4 cyl, 16 valves, VVT-i,
  ETCS-i, 76 hp (57 kW) _at_ 5000 rpm, compression
  ratio 13.0/1
• Motor/generator 500-Volts Permanent Magnet rotor
  AC Sync, 67 hp (50 kW) _at_ 1200-1540 rpm
• Generator/motor 500-Volts PM AC Sync, 34 hp (25
  kW). Starts engine at 1000 rpm when needed. Can
  turn up to 10,000 rpm. A crucial part of the
  Electronic Continuous Variable Transmission
  (ECVT).
• Power Split Device fixed gears that connect
  engine, motor/generator generator/motor to
  provide the ECVT by electronic control.
• Traction Battery 201.6-Volts NiMH, 38 kW (51 hp)
• 5 networked hybrid system computers.
• Net Hybrid System power 110 hp (82 kW)
• Heated coolant when starting
• Regenerative coasting and braking
• Realistic Mileage 40-55 mpg (EPA 60 city/51 not
  so)

1 hp 0.746 kW 1 kW 1.34 hp
12
Toyota 2004-8 Prius Specifications

• Weight 2890 lb (10/lb with all options.)
• People and cargo capacity 825 lbs (374 kg)
• Turning radius 17 feet (Turns around within most
  streets.)
• Coefficient of drag 0.26 (Only Honda Insight is
  lower.)
• Ground clearance 4.9 inches (Not an SUV!)
• Height/width/length 58.1/67.9/175 inches
• Electric reverse motion, initial motion, climate
  control, steering, braking
• Interior size of Toyota Camry
• Exterior size of Toyota Corolla
• 12-Volts battery to start system for
  accessories
• Tires P185/65R15 Goodyear Integrity (low snow
  traction)
• 11.9 gal 450-500 miles per tank
• Uses 87 octane gasoline with up to 10 ethanol
• 0-60 mph in 10.1 seconds
• Top speed 103 mph

13
Toyota 2004-8 Prius Specifications

• Air bags 2 standard 4 more as extras
• Energy-use, climate control and audio 7 display
• Tilt steering wheel
• Warranty Basic 3 yrs/36 kmi Hybrid system 8
  yrs/100 kmi Power train 5 yrs/60 kmi
  Rust-through 5 yrs/unlimited mi Accessories
  purchased with car 3 yrs/36 kmi. Road side
  assistance and hazard insurance 3 yrs/36 kmi
• Excellent navigation system and wireless
  Bluetooth phone connection as an option
• Seats are cloth or leather. Toyota has seat
  covers that are easy to install, with 2 map
  pockets for each front seat. (2006 model offers
  leather seats.)
• Classified as a mid-sized car.

14
Standard Features (23,000)

• Micron-filter 201V electric air conditioner
• Power windows and door locks
• Heated outside mirrors and rear window
• Remote keyless entry
• Cruise control
• 6-speaker AM/FM/CD stereo
• Anti-lock brakes with electronic assist
• Traction control
• Multi-stage dual front air bags
• Illuminated sun-visor mirrors
• Self-leveling headlights
• Much storage space for small items.

15
Optional Features (30,000)

• Front side and roll-sensing curtain air bags
  (front back)
• Intermittent rear window wiper
• Key-less entry start system (Smart Key)
• Vehicle stability control (Automatically controls
  brakes and hybrid system to prevent skidding when
  cornering on a slippery road or turning steering
  wheel abruptly. There is a slip-indicator icon in
  dash display.)
• High-intensity discharge headlamps
• Integrated fog lamps
• Homelink remote transmitter on auto-dimming
  mirror
• 9-speaker AM/FM/Cassette/6-CD stereo
• Immobilizing security alarm
• Floor and cargo mats cargo net
• DVD Navigation system with voice activation
• Bluetooth wireless telephone connection

16
How Does It Achieve Fuel Efficiency?

• Because of electric motor assistance, the engine
  can run at peak efficiency more often.
• Electric motors are more efficient than gasoline
  engines over a larger range of rpm.
• The high voltage (500 V) for the
  motors/generators cuts down resistance loss.
• Deceleration and braking recharge the battery.
• The engine shuts off when not needed for
  example, at stops and down hill. It then
  instantly restarts when needed.
• The engine receives hot coolant before starting,
  which enhances efficiency. Starts at 1000 rpm.
• The body is aerodynamically designed for low drag
  (0.26 drag coefficient).

17
Aerodynamics Underneath
http//privatenrg.com
18
Air Flow Around a Prius II
19
2004 Prius mpg Versus Month of Year
12 mpg difference between January and June
driving in Minnesota. I guess 6 in Virginia.
Location Minnesota. Mix of city, suburban
highway driving. http//john1701a.com/prius/prius-
data10.htm
20
Total Cost of a Prius

• The Prius hybrid system has no clutches or
  friction bands to wear out, contrary to the case
  for a gasoline car. There is nothing in the
  hybrid system to wear out except gears and
  bearings. The hybrid system should last for at
  least 500,000 miles if properly maintained.
• The engine is not stressed nearly as much as one
  is in a gasoline car. So, the engine should last
  for over 200,000 miles if properly maintained.
• The electric motors are brushless designs, so
  they should last for 500,000 miles if properly
  maintained.
• Regenerative braking greatly delays brake pad and
  rotor wear. So, the brakes should last for more
  than 100,000 miles.
• So, cost effectiveness of driving a Prius is as
  much due to the longevity of the hybrid system,
  the gasoline engine, the electric motors and the
  brakes as it is due to higher mpg.
• As important as high mpg is the low emissions of
  a Prius compared to any gasoline car. High mpg
  for a gasoline car does not equate to low
  emissions. A gasoline car optimized for low
  emissions usually has high mpg, but it sacrifices
  performance. Performance is not sacrificed in a
  Prius.

21
How Does the Prius Achieve Low Emissions?

• Since it uses less fuel, it produces less
  emissions.
• Because of electric motor assistance, the engine
  can run at peak efficiency more often, which
  makes emissions lower.
• The engine design (Atkinson cycle, cylinder
  shape, fuel injection and variable firing timing)
  is aimed at low NOx emissions.
• The engine shuts off when not needed at stops
  and going down hills. It then instantly restarts
  when needed. This reduces emissions.
• The engine receives hot coolant before starting,
  which reduces NOx emissions.
• Has bladder-lined gasoline tank to eliminate
  escaping fumes. (Makes it difficult to manually
  calculate mpg.)
• Has lowest emissions rating of any gasoline
  vehicle.

22
Bladder-Lined Gasoline Tank

• Gasoline tank has a plastic bladder liner, which
  expands and contracts as gasoline is added and
  used. This minimized evaporative losses into the
  environment.
• The bladder can become less flexible in cooler
  weather, which will keep you from putting a full
  11.9 gallons in the tank.
• The bladder makes the fuel gauge (guess gauge)
  not very accurate. Always refuel when or before
  the last marker shows on the fuel gauge.
• Filling a nearly empty tank with less than 3
  gallons will not register on the fuel gauge.
• http//i50.photobucket.com/albums/f322/fixmyset/re
  fueling.swf

23
Drive it another 100,000 kms and watch these
differences grow.
Based on 10-years use and 100,000 km (62,000
miles).
http//www.toyota.co.jp/en/k_forum/tenji/pdf/pgr_e
.pdf
24
Prius Life-Cycle Carbon Dioxide Emissions
1 km 0.62 mi 20,000 km 12,400 mi 100,000 km
62,000 mi http//www.toyota.co.jp/en/k_forum/ten
ji/pdf/pgr_e.pdf
25
Toyota Prius 2004-2005

• A series-parallel full hybrid (gasoline
  electric) car

The power split device (PSD) can be regarded as
an asymmetrical differential, for which the two
motor/generators are analogous to the two wheels
that connect to a conventional differential and
the engine is analogous to the crank shaft
(reduction gears in the Prius) going into a
conventional differential.
DC
AC-gtDC DC-gtAC
AC-gtDC DC-gtAC
AC
AC
Engine shaft goes through MG1 shaft to the
planetary carrier of the PSD.
http//www.ecrostech.com/prius/original/PriusFrame
s.htm
26
Toyota Prius 2004-5 Power System
Power-split device
27
Prius Power System
http//www.privatenrg.com
Small generator/ motor
Large motor/ generator Power Split Device
28
Toyota Prius 2004-5 Power Split Device
http//homepage.mac.com/inachan/prius/planet_e.htm
l
Power Split Device 78 teeth in ring gear, 30
teeth in sun gear, 23 teeth in each planet/pinion
gear. (Also called planetary gears, epicycle
gears and trans-axle.)
29
Prius Power Split Device (PSD)
Planet/pinion gears
Ring gearMG2 Wheels
Planetary carrierEngine
Sun gearMG1
Effectively, this and the electronics comprise
the continuously variable transmission of the
Hybrid Synergy Drive.
Notice how small it is!
30
Toyota Prius Hybrid Synergy Drive Control
This contains the DC/AC inverters. Notice the
orange power cables to the traction battery and
to the motor/generator and the generator/motor.
The 5 computers are located at different places
in the car. It is a drive by wire system
similar to modern airplanes.
31
Effective Hybrid Transmission

• The Prius does not have a "true" transmission,
  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
  a transmission. This lack of low-end engine
  torque is replaced by a large electric
  motor/generator and a smaller generator/motor,
  which are connected to the engine in a planetary
  gear arrangement (Power Split Device).
• The onboard computer shifts power from the engine
  and to and from (using the traction batterys
  power) the motor/generators, determining the most
  efficient use of the engine and/or the electric
  motor/generators based on driving conditions,
  accessories in use and when to charge the
  battery.

32
Movement of Power-Split Device Gears
Two cases when the engine is not running.
Moving in Reverse
Starting Engine at Rest
Accelerating Hill Climbing
Cruising
Coasting braking
33
2004-5 Toyota Prius 201.6-Volts Battery
Battery safety plug/fuse
1.31 kWh

• Under the backseat with cooling vent beside the
  seat.
• 28 sealed modules of six NiMH 1.2-Volts cells
  per module. 6.5 Amp-hours.
• Weighs 86 lb (39 kg). Highest output per weight
  in the world (1300 W/kg).
• Charge ranges from 40 to 80 of maximum,
  usually 50 to 70.
• Alkaline electrolyte is a gel that will not
  leak, even in a collision.
• Sealed in a steel case electrically isolated
  from battery terminals.
• Each module is vented underneath in case of
  overcharge gas release.
• All components are recyclable.
• Incentive of 200 for each battery returned for
  recycling.
• Guaranteed for 8 years or 100,000 miles (10
  years/150,000 in California).

34
Prius Battery Module Safety Plug/Fuse
http//www.peve.panasonic.co.jp/catalog/e_kaku.htm
l

• Note the six NiMH 1.2 Volts cells.
• Note the electrical connectors on the ends.
• Note the overcharge gas vent at the bottom left.

Battery safety plug and fuse
35
Charging the Battery at Rest

• Stop the car and set the parking brake firmly.
• Firmly press the brake pedal.
• Set the motion selector to D.
• Press the accelerator pedal most or all of the
  way down. (Only the small generator/motor is
  charging the battery, since the large
  motor/generator is at rest with the wheels. This
  is the reverse of starting the engine at rest.)
• The battery will be fully charged in about 5
  minutes or less.
• You might want to do this before climbing or at a
  rest stop on a long, steep hill for which the
  battery eventually will run out of charge and,
  thus, does not supply power to the motor.

36
Prius 12-Volts Battery

• Turns the hybrid system on by actuating contact
  relays.
• Provides power for the five computers and the
  networks in the car.
• Provides power for the accessories.
• Charged by the traction battery. Can be
  jump-started by other 12-Volts batteries by using
  terminals in the fuse box under left side of
  hood. (When jump-starting other vehicles, best to
  charge the other battery from the Prius battery,
  disconnect the jump and then start the other
  vehicle.) If the 12-Volts battery becomes
  discharged, you cannot move the Prius with its
  front wheels on the ground, because it is in
  PARK.
• Will gradually discharge when car is dormant.
  Decrease the discharge by turning off the
  smart-key switch under the steering wheel. For
  longer dormancy periods use a BatteryMINDer
  (https//www.batteryweb.com/batteryminder.cfm) or
  disconnect the cable from the positive jump-start
  terminal in the fuse box on the right under the
  hood (and lose memory settings). You can buy a VW
  solar battery charger on eBay for parking the
  Prius outside for long periods.
• Batteries maintenance http//www.vfaq.net/docs/TS
  Bs/PG007-03.pdf

37
Locations of Prius Batteries
This is a wrecked Prius that will be shown in
more detail later. Notice the orange power cable
on the left side and the small 12-V battery at
the right rear. There are connections for the
12-V battery under the hood for jump starting.
Battery cooler
Traction battery
http//www.autobeyours.com/0520Prius.htm
38
Prius Gasoline Engine

• 1.497 cc, 76 hp (57 kW) _at_ 5000 rpm, 82 lb-ft (111
  N-m) _at_ 4200 rpm, 4 cyl, 16 valves, VVT-iVariable
  Valve Timing-intelligent, ETCS-iElectronic
  Throttle Control-intelligent, compression ratio
  13.0/1
• Aluminum alloy
• Atkinson/Miller cycle short compression stroke
  (Valves do not close until after the end of
  expansion stroke.)
• Offset crank shaft allows straight down power
  stroke.
• 3 liters of Heated coolant stored near boiling
  point for 3 days used to preheat the engine
  before starting.
• Engine stopped at precise point in cycle to
  minimize stress when restarted.
• Engine is cranked to 1000 rpm and oil pressure
  established before spark is applied first to 2 of
  the 4 cylinders. This takes about ½ second.
• Variable valve timing to optimize efficiency.
• Unique air intake system to reduce manifold
  friction.

39
2004/6 Prius Gasoline Engine
http//www.privatenrg.com
http//www.toyota.com/html/hybridsynergyview/2005/
fall/mpgs.html
http//www.cleangreencar.co.nz/page/prius-petrol-e
ngine
40
Prius Power vs rpm
One can see why the electric motor is important
for power at all, but especially low, rpm.
Small motor extends to 10,000 rpm.
41
Prius Power Train Performance
42
When Does The Engine Run?

• To move the vehicle.
• To charge the traction battery.
• To warm up for lowest emissions.
• To provide heat for passengers if needed.
• To power the air-conditioner compressor if
  needed.
• To run hybrid-system diagnostics.
• Prius misconceptions
• http//john1701a.com/prius/prius-misconceptions.h
  tm

43
Smooth Acceleration
44
Regenerative Braking
ECB Electronically Controlled Braking System
which controls the coordination between friction
braking and regenerative braking, which
preferentially uses regenerative braking.
Recovers up to 90? of the possible recoverable
energy down to 7 mph. Each wheels brake is
independently controlled electronically.
Hydraulic backup brake control is on the front
wheels.
45
To B or not to B
The B selection on the motion selector causes
the engine to turn without firing, using air
compression and engine friction to turn some of
the vehicles motion energy into heat. Some of
the motion energy still goes into charging the
battery, but not as much as when B is not
selected. (After using B you will need to reset
the cruise control.) When might one use B?
B engine braking.
Be sure to move the motion selector back to D
after using B, or you will decrease the mpg for
normal driving.

• When the battery is fully charged all battery
  bars are green and you want to slow down.
• When a sign says Trucks use low gear.
• When going down a steep hill and the cruise
  control cannot hold the car to less than 5 mph
  above the speed setting.

46
Constant Driving in B

• Some owners of Prii drove all the time in B. I
  know of two examples of this.
• They complained that the mpg was low.
• The reason is that the engine spins at high rpm,
  without firing, going down hills and when
  braking, instead of turning off.
• It is an easy mistake to make, since the B
  position is straight down from the rest position
  of the movement selector. One has to move it to
  the left and then down for D.

47
Towing a Prius

• Do not leave the front wheels on the ground when
  towing if hybrid system is not on and in neutral.
  Doing so could damage the hybrid system.
• Towing hook for front is in cargo storage box
  screw it into covered hole in front bumper.
• Best to use a flat-bed tow truck and raise the
  front wheels before pulling the Prius onto the
  truck.
• Two tie-down hooks are under the back, do not use
  them to tow the Prius from the back. Can be
  replaced by a tow bar for a bicycle rack.
• Do not allow towing or tie-down chain attachments
  to car frame always use the front tow hook and
  the back tie-down hooks!
• If it must be towed with front wheels on ground,
  turn on hybrid system and put hybrid system in
  N and have someone guide it and work the
  brakes.
• Towing by Prius should not be done! (Some have
  towed small trailers with a tow bar.)

48
Towing a Prius

• Best way to put a Prius in Neutral to tow it with
  all wheels on the road
• Press the power button twice without pressing the
  brake (IG ON mode).
• Put foot on brake and shift into Neutral.  Hold
  the motion selector in Neutral for 3 seconds.
• Then it can be towed with the wheels on the road.

49
Prius as a Powerful Computer Network

• There are many Local Area Networks (LANs)
  connecting 5 computers in the vehicle. (All new
  vehicles have powerful computers and networks
  hybrids take that one giant step further.)
• The LANs communicate through super networks.
  E.g., the climate-control network and the braking
  network communicate with the power-train network.
• For the keyless entry start option, the
  vehicles main computer powers up using the
  12-Volts battery when you approach the vehicle.
  When you press the Power button the other
  computers and LANs are turned on, powered by the
  500-Volts traction battery.
• Pressing on the accelerator activates the motive
  networks according to the movement selection.

50
Prius as a Powerful Computer
ECU Electronic Control Unit 32-bit computer
SOC State of Charge of traction battery
See http//www.hybridcars.com/computer-control-sys
tems.html and http//techno-fandom.org/hobbit/car
s/bodyecu
51
What Happens When Your Press on the Accelerator?

1. The motive power demand from depression of the
   accelerator pedal (not the "throttle") goes to
   the Hybrid-ECU.
2. The Hybrid-ECU also gets power demand from the
   battery-ECU ("charge me" or "discharge me"), the
   air conditioner, etc.
3. The Hybrid-ECU decides where to get this power
   from, the ICE or the battery. If it wants power
   from the ICE, it sends a power demand to the
   Engine-ECU.
4. The Engine-ECU figures out how to get that much
   power from the ICE at the best efficiency and
   tells the Hybrid-ECU its choice of spin (torque)
   so that MG1 can be controlled appropriately.
5. The Hybrid-ECU controls MG2 to add or subtract
   power at the final drive as necessary.
6. Electrical power generated or consumed by MG1 and
   MG2 will result in a net surplus or deficiency
   that is provided or absorbed by the battery. In
   theory, this will correspond to the battery-ECUs
   charge demand (see 2 above) but in practice there
   is much lee-way for things to come out
   differently and other power demands still to be
   met exactly. In a sense, the battery makes up the
   error.

52
15 Computers in a Loaded Prius
53
Prius Safe Computer Hacks

• Turn off the backup beeper
• Cycle ODO/TRIP, stopping on ODO.
• Power off.
• Power on, within 6 seconds, hold ODO for at least
  10 seconds.
• While still holding ODO shift into Reverse and
  back into Park.
• "b-on" shows on display, press ODO to cycle to
  "b-off".
• Allow navigation destination parameters to be set
  while moving
• Press the "Menu" button (hardware button).
• Press the "Voice" icon on the display.
• Press the upper left corner of the display, where
  the speaker icon is.
• Press the lower left corner.
• Press the upper left corner again.
• Press the lower left corner again.
• The screen should change to a diagnostic screen.
• Hold the "Override" button for several seconds
  until it changes to black and a beep is heard.
• Press the Back button.
• This will be in effect only until the Power is
  turned off.
• Warning do not play with things on this screen
  that you don't know about!

54
Prius Electric Safety

• Battery is placed between the frame rails and in
  front of the axle where it is least likely to be
  damaged in an accident.
• High-voltage cables are metal shielded, orange
  colored and placed away from possible damage in
  collisions.
• Battery power is cut off when an air bag deploys
  and other collision sensors activate.
• Vehicle does an electric system check when
  powered up.
• Toyota provides special pamphlets for emergency
  personnel http//techinfo.toyota.com/public/main/
  2ndprius.pdf
• See http//www.asashop.org/autoinc/april2004/colli
  sion.cfm http//www.asashop.org/autoinc/aug2002/sp
  ecial.cfm
• See http//autos.groups.yahoo.com/group/toyota-pri
  us/message/8834 for information about the
  difficulty of getting shocked by a Toyota Prius.

55
Prius Electric Safety
Battery shut-off relays.
A ground-fault monitor keeps the car frame from
being accidentally charged.
Fused safety plug Pulling it out turns off the
high voltage.
56
Hybrid Reliability

• Consumer Reports listed Toyota Prius and Honda
  Civic hybrid among the most reliable vehicles for
  2005 models.
• Toyota Prius traction batteries regularly last
  for over 200,000 miles driving. Should last 15
  years.
• The Toyota Synergy Hybrid System is much simpler
  mechanically than gasoline vehicles (no
  transmission). The complexity is in the
  electronics, which is highly reliable.
• Engine does not always run, standard brakes are
  not always used for stopping and there is no
  starter or alternator to wear out. Brakes should
  last 100,000 miles.
• Early 2004-5 Toyota Prii had a software problem
  that caused the engine to stop. (EV still worked
  to move vehicle.) A software download fixed the
  problem after 68 known incidents of engine
  stalling. http//news.yahoo.com/s/ap/20051013/ap_o
  n_bi_ge/prius_recall_1
• http//home.comcast.net/bskattebol/50p.pdf
• http//www.earthtoys.com/emagazine.php?issue_numb
  er05.08.01articlenaftc
• The modular design of the Toyota Prius allows
  defective modules to be quickly diagnosed and
  replaced.
• Prius Maintenance http//john1701a.com/prius/priu
  s-maintain04.htm
• http//www.artsautomotive.com/Hybrid.htm
• Car Talk Prius excellent review
• http//www.cartalk.com/content/testdrives/Reviews
  /toyota-prius-2004.html
• I have had one 2005 Prius recall to replace the
  steering column.

57
Prius I Engine Efficiency
1500 rpm 2200 rpm 3000 rpm
Peak efficiency is at about half power. The
sweet spot.
Worst efficiency is at low power.
Better to floorboard than to creep!
http//techno-fandom.org/hobbit/cars/prius-curves
.gif
58
http//john1701a.com/prius/presentations/prius_ths
-presentation_07.htm
59
Differences in Driving a Prius

• Power button starts the hybrid system, rather
  than a key. The key fob must be somewhere in
  the car for smart start option in the fob slot
  otherwise.
• Engine does not start immediately after system
  power is turned on it starts about 7 seconds
  later to warm up the engine, then shuts off a few
  seconds later if not needed.
• Engine turns off at stops and when going down
  hills also it does not provide power for backing
  up.
• Creep is built in at stops, provided by the
  electric motor. It is increased on an upward and
  downward slope to hold car in place. It can be
  turned off by pressing the brake pedal or putting
  the movement selector in the Neutral position.
• Slight sounds occur after stopping the car as hot
  coolant is pumped into the thermos container.
• Electric whine during slows starts and braking.
• Special Brake position of movement selector to
  cause engine braking.

60
How to Drive a Prius Efficiency

• Use Pulse Driving
• Accelerate rapidly at about half power, because a
  brief medium engine load uses less fuel than a
  prolonged low engine load. Best is when only the
  engine is moving the vehicle.
• Decelerate slowly well ahead of the stopping
  point to maximize brake regeneration. Best is
  when neither engine nor motor is moving the
  vehicle and the battery is not charging
  (gliding).
• Keep the vehicle in a garage during cold weather
  because a cold vehicle reduces brake
  regeneration.
• Keep tire pressure at recommended levels or
  higher to reduce tire friction losses. I up them
  by 2 psi.
• Steady 55 mph (55-60 mpg) is the point of peak
  efficiency. 75 mph 40-45 mpg. For every mph
  faster than 55 mph, fuel economy drops by about 1
  percent.
• http//home.earthlink.net/graham1/MyToyotaPrius/D
  riving/Economy.htm

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Driving for Lowest Emissions and Highest MPG

• MPG is much lower for the first 5-10 minutes of
  driving, because the engine is run until it
  reaches the best temperature for the lowest
  emissions. So, combine short-trips to save
  gasoline.
• MPG, as for all new cars, increases as the miles
  are driven up to about 10,000 miles.
• Higher tire pressurehigher MPG. Maximum pressure
  for the tires44 psi. (Standard35 front/33 back)
  Should be 2 psi greater in front than in back. I
  use 38/36 many use 42/40.
• Use cruise control when possible to get best MPG.

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MPG versus MPH for 2003-8 Prius
Note the big decrease in mpg above 70 mph!