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Toyota Prius

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Comments

  • john1701ajohn1701a Member Posts: 1,897
    > Law of conservation of energy

    Yup, energy isn't free. But that the system has been proven to run perfectly fine with a damaged non-functional module. The loss of wattage makes no difference to operation, only efficiency.

    And sorry, I don't have numbers available for that. The only detail I've seen was for the amps in warm verses cold measurements. The amp draw was allowed to be much higher in the colder, likely due to not having to worry about cooling needs.

    > The Prius has an inverter because the battery pack puts
    > out DC current and the motor is AC.

    It also increases the voltage, since the pack itself is only 201.6 volts.

    > A better system would have been to keep the battery warm.

    Yup to that too; however, electricity comes primarily from the engine anyway. So it isn't really as bad as it could be.

    JOHN
  • quasar4quasar4 Member Posts: 110
    Has anyone noticed a creaking/rattle/buzzing noise at any time when driving? I usually notice it when I'm going slow and accelerating. It lasts for about 3 seconds. It's not the same sound as the motor makes when you shut off the power.

    Also curious about the daytime running headlights. The owner's manual says that they'll engage when the parking brake is disengaged --even with the headlight switch in the OFF position. Doesn't seem to work for me (I have a package 7).

    Oh, and concerning the cold weather low mileage discussion, one other factor could be oxygenated gasoline which I believe is mandated in certain areas of the country during the Winter months to reduce air pollution. The gas mileage of my old Honda would always drop after filling up with the modified fuel.

    Thanks
  • hybriddriverhybriddriver Member Posts: 23
    > the system has been proven to run perfectly
    > fine with a damaged non-functional module.
    > The loss of wattage makes no difference to
    > operation, only efficiency.

    This is true. Whether the loss of wattage is from a damaged module or cold battery pack, the system will compensate and still operate. The only thing is efficiency will go down which means less MPG.

    > electricity comes primarily from the engine
    > anyway. So it isn't really as bad as it could
    > be.

    Perhaps it isn't really as bad as it could be in steady speed highway driving, but the battery pack is needed to store recaptured electricity from regenerative braking. So if the battery pack efficiency goes down then so does MPG in city driving.

    I am just trying to help people understand why cold weather makes MPG go down. All in all, the Prius is still a wonderfully engineered car that overall excells in MPG. Hybrid technology is still in it's infancy and eventually all of it's quirks, problems and whatever will be worked out. Until then there will still be plenty of people lining up to buy them. Probably more than supply can meet. I even bought one! And I love it because this is cutting edge personal transportation technology long overdue and to be part it is an experience in it's own! It is also a gratifying experience to know you are doing the right thing for the environment and the future.
  • john1701ajohn1701a Member Posts: 1,897
    > I am just trying to help people understand why cold weather
    > makes MPG go down.

    No problem... except the most important fact hasn't been pointed out yet. The battery-pack only takes a few minutes to warm up anyway. Using it creates heat. So the cold is rapidly eliminated.

    It's like the recharging. That only takes a few minutes too. The common misconception is that it takes much longer.

    JOHN
  • talleyidtalleyid Member Posts: 34
    "Has anyone noticed a creaking/rattle/buzzing noise at any time when driving? I usually notice it when I'm going slow and accelerating. It lasts for about 3 seconds. It's not the same sound as the motor makes when you shut off the power."

    Yes I have. I have no idea what it is but assumed it was just the normal vehicle operations taking place. I am curious though!!? I think it seems to be coming from the engine compartment near the speedometer area.
  • gscheil1gscheil1 Member Posts: 72
    DRL's are not available on U S cars, only on those shipped to Canada.
  • umpireumpire Member Posts: 12
    I am in the market for a new vehicle, an I sat in a Prius yesterday. It looks like a good car, but I'd like your opinions of this vehicle on the questions below and any other topics you can think of.

    I appreciate your help!

      
    Do you really get 55 mpg?

    How is the ride/handling?

    Does it seat 5 comfortably (I really need this)?

    Have you experienced mechanical problems? If so, what?

    Does the build quality seem adequate?

    Do you think it will hold up over 100,000 miles?
  • wwestwwest Member Posts: 10,706
    The boost to 500 volts is there because of the above. The inductance, copper windings, in the electric motor are highly resistant to current flow, much more so tha a simple resistor of equal resistance. Applying a higher voltage initially, only until the current flow rises to a more desireable, design, level, improves the efficiency of the electric motor drive system dramatically.

    Assuming some method is provided to "artificially" limit the current flow, applying more voltage, even a BILLION volts, would result in a quicker generation of torque in an electric motor.
  • hybriddriverhybriddriver Member Posts: 23
    > Does it seat 5 comfortably (I really need this)?

    Try sitting in the back seat and see if you have enough head room. The sloping hatchback design takes a little away from this. Otherwise it has lots of room.
  • talleyidtalleyid Member Posts: 34
    >Do you really get 55 mpg?

    I'm in the St. Louis area with aprx. 1600 miles on my vehicle. I commute 33 miles each way primarily on Interstate with some rush hour stop and go. I'm currently averaging between 46-49MPG.

    >How is the ride/handling?

    The ride is one of the smoothest of any vehicle I've personally owned. Handling has been great. Obviously this is just my opinion. I've had a close call with an inattentive lane changer and the rear tire of a vehicle I was passing, when it fell off, and the vehicle remained stable in both situations while I swerved all over creation.

    >Does it seat 5 comfortably (I really need this)?

    I'm not sure of the size of the 5 people but the backseat legroom is greater than any vehicle I've been in. I'm 6'3" / 260LBs. and the vehicle is comfortable to me. I had a backseat passenger the other day, 4 adult men, who is 6'3" or so and 300LBs. and I heard no complaints from anyone. Just "look how big that backseat area is."

    >Have you experienced mechanical problems? If so, what?

    None. I did have a minor issue that has been reported by several people where I got a check engine light after about 40 miles that stayed on for about 60 miles. This has been reportedly due to an oil protective coating on the exhaust system that "burns" off during highway driving. No noticeable change in the vehicle operation during the "check engine" phase. I believe it is said to be related to a sensor being obscured until the coating burns away.

    >Does the build quality seem adequate?

    Build quality is superior in my opinion. Toyota is one of the only vehicle makers that has consistently rated above Subaru (we've had 5) in reliability and quality. This is my first Toyota and I'm extremely impressed. The Prius specifically is built very tight and you can even get a sense of the solid construction by just closing the door.

    >Do you think it will hold up over 100,000 miles?

    Considering my Subaru vehicles held up over 100,000 and this vehicle is reportedly, and apparently, better quality I would say yes.

    Hope this info helps in your decision.
  • hybriddriverhybriddriver Member Posts: 23
    > The battery-pack only takes a few minutes to
    > warm up anyway. Using it creates heat. So the
    > cold is rapidly eliminated.

    Any proof that the battery pack only takes a few minutes to warm up? Does your's have a temperature sensor in it? I know that batteries create their own heat during use. But if it is severely cold, since hybrids do not use the battery pack constantly, I really wonder about this. Many people complaining about poor MPG in the cold are reporting that they are driving mainly in the city with lots of stops. Reduced battery efficiency would account for this since the battery pack is used most here to recapture energy during braking and help in acceleration. But with steady speed highway driving it's mostly energy from the gas engine so the MPG drop there is not as bad. Maybe someday we'll here what Toyota has to say about cold weather performance. Click on this link to learn more about Why Do Batteries Discharge More Quickly in Cold Weather and what they say can be done about it: http://chemistry.about.com/library/weekly/blbattery.htm
  • hybriddriverhybriddriver Member Posts: 23
    > applying more voltage, even a BILLION volts,
    > would result in a quicker generation of torque
    > in an electric motor.

    Yes, you are right. But we were talking specifically about cold weather performance. I really don't think Toyota designed the car to ONLY provide a quicker generation of torque in cold weather. Why not do it when it's warm weather too? The inverter bumps the voltage up to 500 volts from lower battery voltage because it was designed as a 500 volt system for the reasons you mentioned and not just during or for cold weather.
  • geogirlgeogirl Member Posts: 24
    Umpire,
    I got my new Prius on Dec. 24 so I have limited experience driving the car, but I LOVE this car! The ride is smooth and comfortable. On my first tank of gas I averaged 44 mpg (temperature was in the 20's and for a few days only in the single digits). I'm on the second tank now and weather has warmed to 40's up to 60(daytime)with mornings in the 30's and my mileage so far for the last 250 miles is at 50 mpg. As far as room, very roomy in the back seat - my husband 6'2" fits easily. However, if you are over 6' you should try this for yourself as some have reported head room problems. Also if you need to fit 5 adults routinely, you need to be looking at larger cars! This car is the typical mid-size car where it can seat 4 comfortably, but anyone other than a child in the middle rear seat - good luck! As far as mechanical problems - none; build quality - very solid; and I bought mine with the idea that I would have it for more than 100,000 miles. Considering that the battery is warranted for that long, I think Toyota thinks so too. Just want to add - this car is fun to drive. I have no regrets. Good luck with your decision.
  • gscheil1gscheil1 Member Posts: 72
    Does the 2004 really have the warning? Recently I had a screw in a front tire and the pressure got down to 11 pounds and nothing happened.
  • hans000hans000 Member Posts: 19
    Don't seem to have that. I didn't see it mentioned in manual. (That's not much though: the horn is not mentioned. The worst part of this car, IMHO, is the manual.)
  • hans000hans000 Member Posts: 19
    No kidding. I can trigger the lurching by just raising cabin temperature even after it's reached previous set point (75F). It comes and goes together with the blower speeding up/down.

    During cold (50F, N. CA) start and the car stopped, it feels like ICE is still running but the display shows not. I am curious what's causing that vibration, ICE or AC compressor?

    I doubt it's the coolant pump. On conventional car(should be the same on Prius) the pump is similar to a blower: it doesn't vibrate. The vibration/lurching is the signature of piston/cylinder thing.

    ===============
    texassalsa04 wrote:
    ...well, I did a test this morning in my Prius while driving to work. Temperature outside was about 49F. I had the "Auto A/C" off as well as fans/blower in off position. The lurching continued as usual. So, fromt this non-scientific test, I would say that the lurching is not due to having the heater or fans on etc...it must have something to do with what John had posted earlier...hot coolant pumping through the engine warming it up etc...
  • dc8527dc8527 Member Posts: 12
    Thanks hybriddriver for the extensive analysis on low MPG in the cold! We need to face an issue, dig into it and try to come up with solutions. I called Toyota today. It has not published any solution.

    There are 8 bars in the battery gauge. When it drops 2 or more the color changes from green to blue. It is blue most of the time on my 04 Prius. How about yours and others' from warm and cold climates?

    I believe the computer instructs the gas engine and the electric motor to charge the batteries more often when they are in blue, hence more gas consumption in this regard.

    Does anyone know how the battery gauge work? Measuring the voltage drop is the easiest, but may not be the best estimate of how many charges are left in the pack. Measuring the internal resistance of the pack may be another way, yet it still is not a direct measure of the charges left.
  • oldfoxoldfox Member Posts: 29
    Maybe somone who knows more than I about the Atkins cycle engine can answer my question.

    Why does a 2cy engine only get 7 mpg? I see this all the time on my screen - not just 7 mpg but 13 -23-10 etc. Seems to me a 2cy should get much better even from a dead stop and even not using the battery (Yes, I know the battery starts the car but hope you understand the question)
  • umpireumpire Member Posts: 12
    geogirl and talleyid,

    Thanks for the responses. They have me ready to order one today!

    One other question I need answered. I tend to drive faster than the speed limit.

    How does the Prius perform at speeds of 75 and higher?
  • hybriddriverhybriddriver Member Posts: 23
    Are my batteries in the blue most of the time? Well, guess what, I have the other hybrid. The Honda Civic. So unfortunately, I cann't answer that question. I live in Northern California where it is usually warm so I don't even have severe cold data. But I am glad that you appreciated the info I posted.
    :)
    Half of a solution to a problem is to first identify exactly what is wrong. In this case the problem is cold battery pack in severe cold weather greatly diminishing city MPG. It is now up to Toyota to implement a fix or if that is not possible, redesign it for future models.
  • peggyloupeggylou Member Posts: 40
    There have been many posts here of people who get about 42 mpg instead of 50-60 as advertised. Is there anyone out there who lives in Ca? What kind of mpg does the Prius get in the warmer climates? Even 42 is great, but I know I would be disappointed to get so far off the claimed mileage.

    Also, what do you guys think about all that hard plastic in the interior? My first impression was that it was "stark" (to be polite). Does one get used to it? My teenage son is nagging me to get the Prius over the CR-V or Matrix, apparently he thinks he will look cool going to school in a Prius.

    Anyone have experience using this car as a family hauler, with 2 kids and small dogs? Is there enough room for the kids and "stuff"?
  • john1701ajohn1701a Member Posts: 1,897
    > Half of a solution to a problem is to first identify
    > exactly what is wrong.

    or IF IT IS ACTUALLY A PROBLEM!

    In this case, it isn't. Keeping the charge at that level is the best possible thing Toyota could do. Not overcharging or deep-discharging yields the longest possible battery-pack life.

     
    > In this case the problem is cold battery pack in severe
    > cold weather greatly diminishing city MPG

    You better check your facts, because they aren't correct.

    Heavy stop & slow city driving will drop the MPG regardless of temperature. Just ask those getting low efficiency right now down in LA, where it's quite warm. Then ask how I'm maintaining a 43 MPG average here in Minnesota, where it's rather cold right now. And the same goes for the previous 3 winters too.

    JOHN
  • nippononlynippononly Member Posts: 12,555
    and 500 miles, my rented Prius had the batteries in the blue most of the time. Occasionally I would get one bar short of the top, and they would turn light green. If you think about it, this makes sense. The car wants to use the electric boost as much as possible to increase gas mileage, but does not want to deeply discharge the battery pack, so it tries to balance the charge somewhere near the middle. The charge on mine never dropped below half.

    "Also, what do you guys think about all that hard plastic in the interior? My first impression was that it was "stark" (to be polite).".......I agree! Although if you think the Prius is stark, get a load of the interior of the Matrix some time!

    "What kind of mpg does the Prius get in the warmer climates?".......in the end, I averaged 45.5 mpg. A lot of that was highway driving, which is not where Prius truly shines. For all in-town driving, you would do better due to shutdown at stops and while braking.

    "How does the Prius perform at speeds of 75 and higher?".....very well, actually. I took it up to very high speeds to see what it could do, and above 55 mph, it accelerates better than my Matrix. Plus, it is better insulated (than the "classic") from the sound of the ICE racing when you accelerate rapidly. Not to mention that from a stop, I accelerated uphill to 75 mph, and was able to beat a new 4-cyl Camry, and a new F-150 pick-up.

    "Why does a 2cy engine only get 7 mpg? I see this all the time on my screen - not just 7 mpg but 13 -23-10 etc."........this is because you are seeing instantaneous mpg readings, rather than readings over a few miles (I assume you are talking about the rapidly changing readings on the "consumption" portion of the trip info readout). If your own car now had this same type of display, it would also show readings of just a few mpg whenever you accelerate hard. Check out the little mpg gauge on a BMW whenever you floor the accelerator...

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • talleyidtalleyid Member Posts: 34
    I haven't actually driven my vehicle over 70 for any extended period. I'm borderline compulsive about conserving fuel and tend to drive between 60-65 unless traffic speed makes that too hazardous.

    During the times I've driven 65 mileage has seemed consistent with my previous statements. As I'm sure you're aware you are going to pay some penalty in mileage because the faster you travel the higher your wind resistance, etc. becomes.

    I've found that if I calculate the time savings under best conditions I'm only saving about 2-3 minutes by driving 65 instead of 60. Again you have to take into consideration the common speed of traffic but the fuel savings and additional reaction time, and control, I have at lower speeds makes me more than willing to use 2 more minutes.

    Example, my 33 mile commute takes about 40 minutes total at 60MPH. I increase to 75 that's 15 miles more in 1 hour. That's 7.5 miles more in a half hour which means I'd save about 5 minutes. Some of my 40 minutes is just getting to the highway. I've found this has made me personally a much more relaxed driver and I'm saving a little money on fuel! Hope I don't sound preachy just wanted to pass along some info!
  • lalalalalalalalalala Member Posts: 30
    has anyone driven their Prius during a tropical storm yet? how does it hold up in heavy rain?
  • john1701ajohn1701a Member Posts: 1,897
    Sorry, I don't have any 2004 rain data to share. It's the wrong season for that. But I can point out facts about my 2001 in the rain.

    Humidity is the engine friend. That moisture sucked into the cylinders helps with efficiency when super-heated. So you get more bang for your buck with piston power in the rain. The problem was the windows would steam up, so you'd have to run the defroster. In the 2001, that meant the engine would remain running when you stopped resulting in a MPG loss. But with the 2004, the defroster is powered by the battery-pack instead. So I bet I'll enjoy very pleasing MPG in the rain... when it finally warms up.

    Handling is no big deal, just like any other Toyota car.

    The HID lights should be an obvious plus at night in the rain. They are with the snow.

    JOHN
  • hans000hans000 Member Posts: 19
    The first tank of gas was 42MPG. With a heavier foot it's down to 38. All by the display. Most trips are 10 miles one-way, mixed highway/local with 800ft elevation change. It's in San Jose.

    It's not too bad. My '97 Taurus got 19MPG; '02 Corolla (3-speed auto) got 25. The elevation kills MPG.

    Toyota did a good job to make hard plastic look ok. The places you touch are still soft. Granted, same or less amount of money can buy a Camry with nicer interior. "Green" does cost extra. (I would say $3k more compared to Scion. Did your son check that?) Prius is fun to drive compared to Camry or Taurus. Hatch back can fit a lot of stuff. People hauling is between Camry and Corolla.

    By the way, people were talking about "2 cy" engine. What's that? Prius has 4-cylinder, 4-stroke, Atkinson cycle engine. The following link explained it very well:
    http://home.earthlink.net/~graham1/MyToyotaPrius/Understanding/In- ternalCombustion.htm
  • geogirlgeogirl Member Posts: 24
    My battery gauge is almost always in the blue - usually in the same range of from two bars from the top to one bar below the half. Only once has it dipped to the lowest level when I was running on electric only through a paid drive-thru Christmas light display. At that time, the battery had to be recharged using the ICE.
    As far as going green - It has charged up to green several times (showing all green, but missing one bar at the top), but only stays green for a very short time before dropping back to blue.

    On my test drive I got the car up to 75 mph going up a steep incline on I-70 in Colorado. The car did fine, but gas mileage will definitely take a hit driving this fast. I have been trying to stay below 60 mph in my new car until the car is "broken in". On the highway this is not an easy thing to do.
  • umpireumpire Member Posts: 12
    talleyid, thanks again. I tend to drive somewhere between 65-72 and most of my miles are rural interstate. However, my climate will be close to yours as i live in western Illinois, so it gives me a good comparison.

    May I ask where you purchased your Prius? Were you satisfied with the dealer, your treatment, and the price? St. Charles is about 1 1/2 hours for me, so I could easily car shop in that area.

    "Also, what do you guys think about all that hard plastic in the interior? My first impression was that it was "stark" (to be polite)."

    I like the "stark" interior. It makes the inside look clean and finished. It's that whole "form follows function" thing. The plastic could be more attractive, but the lines of the interior are superb.
  • ragueroraguero Member Posts: 60
    I drive back and forth 30 miles each way to work in the LA area. I have been averaging 47 mpg on the dashboard display which I am very happy with. I have about 2500 miles on my Prius. Peggylou, I have one 15 yr old kid (with her best friend glued to her so it may as well be two) and one dog. There is plenty of room in the car and cargo space for just about anything.
  • hybriddriverhybriddriver Member Posts: 23
    > or IF IT IS ACTUALLY A PROBLEM!

    You are right. I don't know with 100% certainty. I only know what I read here. It is up to Toyota to perform the scientific testing and give up concrete results. I can only suspect causes. But I am after the truth.

    > Keeping the charge at that level is the best
    > possible thing Toyota could do. Not
    > overcharging or deep-discharging yields the
    > longest possible battery-pack life.

    I agree, but that is not the point. The point is about reduced battery efficiency in severe cold weather which translates into reduced MPG. If you have to please reread what the person with a Ph.D. in chemistry says about it and what can be done about it: http://chemistry.about.com/library/weekly/blbattery.htm

    > Heavy stop & slow city driving will drop the
    > MPG regardless of temperature. Just ask those
    > getting low efficiency right now down in LA,
    > where it's quite warm. Then ask how I'm maintaining
    > a 43 MPG average here in Minnesota, where it's rather
    > cold right now.

    I don't agree. I recall post# 2167. I will repost part of it here: <start> I went from Fresno to Orange County, in Cailf. I set the cruise @ 65,and it was 70 degrees outside and I had about 1 hour of stop and go traffic in down town LA. I went 290 miles. It took just 5.54 gals. That's 52.3 MPG.The 04 Prius got the best MPG in stop and go traffic. <end> This clearly states the Prius got the best MPG in stop and go traffic. Therefore, greater than the 52.3 MPG average for the entire trip. And you said your's is 43? Your claim is false.
  • dc8527dc8527 Member Posts: 12
    "The test used to determine the city fuel economy estimate simulates an 11-mile, stop-and-go trip with an average speed of 20 miles per hour (mph). The trip takes 31 minutes and has 23 stops. About 18 percent of the time is spent idling, as in waiting at traffic lights or in rush hour traffic. The maximum speed is 56 mph. The engine is initially started after being parked overnight. Vehicles are tested at 68 F to 86 F ambient temperature."

    EPA ran that course in their lab on 04 Prius and marked down the result by 10% for the published espitmate of 60 MPG.

    The city MPG's we have seen reported here are nearly all in the 40's, about 25% to 33% lower than the estimate on average. My city and highway MPG's of a conventional car (93 Eagle Summit Wagon, same as Mitsubishi Expo LRV) were about 10% better than EPA estimates in summer when the car was new and 10 years old. These MPG's precisely matched their lab numbers.

    A Toyota Rep at 1-800-331-4331 told me on December 17, 2003 that their engineers were working on it and there would be an answer by mid Jan 04. But there was not a published solution so far, another Rep told me yesterday. "I would be concerned if it was my car", the Rep said.

    We, true Prius owners and possibly dealer's agents here, need to face the issue.
  • john1701ajohn1701a Member Posts: 1,897
    > And you said your's is 43? Your claim is false.

    That's not what I was referring to at all. It was a LA owner on the Yahoo forum, contributing far more detail then what's available here, hence the confusion. And now, I don't even remember what the heck the original topic was anymore. Apparently, summarizing doesn't work either.

    Plain & Simple: stop & slow sub-30 MPH traffic is the worst. 70+ MPH highway cruising is nasty. 35 to 55 MPH suburb driving with occasional stops is the best. Cold weather lowers efficiency (and I have 4 years of winter data to clearly showing that).

    JOHN
  • m4ethm4eth Member Posts: 101
    Toyota should re-define what they mean by City and Highway driving...John stated that Suburb driving (35-55) with occasional stops is best...

    I would define CITY driving as 0-35mph with many stops or holds (stop lights as well as heavy traffic in which you must stop regardless of lights).

    HIGHWAY would mean cruise speeds of 65-70 mph with minimal or no stops.

    So the Pruis in heavy traffic behaves the same as any all combustion vehicle...and you don't get the opportunity to regenerate in stopped traffic (all power plants now equal at this point) ...regeneration only occurs during the braking...grabbing the kinetic energy during the stopping process, once you stop this energy of motion is gone ... so is the regeneration!

    Mike

    Mike
  • john1701ajohn1701a Member Posts: 1,897
    > 35 to 55 MPH suburb driving

    Except I made a mistake... it's actually 35 to 50.

    55 MPH is still better than 60 though.

    Sorry about that.

    JOHN
  • ragueroraguero Member Posts: 60
    Maybe it's the WAY everyone drives that most affects MPG. My 30 mile commute is at 0-30 mph for about 15 of it and 65-75 for the other 15. I am getting about 48 mpg here in warm L.A. I'm not a leadfoot although I do accelerate quickly to keep up with traffic, a necessity in LA traffic. I imagine the posted "estimates" are done under very strict and easy conditions. No testing can meet all qualifiers.
  • john1701ajohn1701a Member Posts: 1,897
    > if you just cruise down the highway then you are not
    > braking and thus regenerative energy is not recovered

    Braking is not required for the recapture of energy.

    I prove this routinely. Without touching the brakes at all while just going with the flow on the highway, I earn "leaf" symbols on the Multi-Display indicating how much was regenerated.

    Any excess kinetic energy can be reclaimed, any minor decline will cause this.

    It is amazingly easy for the Planetary-CVT in Prius too. Rather than using the 50kW motor (MG2) like it does for braking recapture, it instead uses the 10kW motor (MG1) since that is ALWAYS spinning while the engine is providing thrust anyway. The switch-over from generating electricity from the engine to from the wheels completely seemless, since everything is already moving. The electric flow doesn't even change. All that actually happens is the sensor detects thrust coming from the wheels instead of going to them and eases up on the engine RPM.

    JOHN
  • wwestwwest Member Posts: 10,706
    Nothing in life is free!

    Regenerative braking slows the vehicle down. If you intended to stop or slow for some reason anyway that is all to the good. But the use of regenerative braking while cruising down the highway would simply defeat the purpose.

    AND.

    Just suppose that Toyota was smart (or devious) enough to start the DOE/EPA mileage test series with the batteries "full" and end with them empty?

    Who's to know?

    I rather doubt if the rules and regulations cover that issue yet.
  • wwestwwest Member Posts: 10,706
    Regenerative braking so as to not overspeed on a decline (assume downhill run) isn't regenerative braking at all.

    So, John, just what do YOU call it then?

    Or you assuming that since your braking foot is not involved it should be called recovery of kinetic energy?
  • geogirlgeogirl Member Posts: 24
    I don't think you can blame Toyota. EPA does the testing and makes the definitions for city or highway driving! The EPA testing should just be used as a basis for comparison of vehicles which were all driven under the same testing circumstances and not be taken for actual mileage. I guess I'm not understanding what all the fuss is about. Most people do not get what the EPA mileage says on their cars and even the EPA states that your mileage may vary. If the EPA mileage stated 34 mpg for a car and you got 28 mpg, would you be complaining? Well, that's about 16.6% less - so is 50 mpg compared to 60 mpg.

    I also agree with raguero that the WAY each person drives is a HUGE factor especially with the Prius. Since the Prius offers you instantaneous feedback, I, like many others who drive the Prius, try to maximize the mpg by changing how they might normally drive. I find that I am driving the speed limit more now than before the Prius as well as letting up on the gas to coast whenever possible. I just absolutely LOVE to see that 99.9 mpg pop up.

    <So the Pruis in heavy traffic behaves the same as any all combustion vehicle...> I disagree with this. When you are stopped at a light or in traffic, the gas engine shuts off so you are not polluting or burning gas.

    <regeneration only occurs during the braking>
    During that stop and go, you are regenerating when you put on the brake. The energy you recaptured is stored in the battery - it is not lost. Also if you go downhill, the battery can charge without putting on the brake. I think I have also seen this when cruising on the highway if I am not accelerating.
  • nippononlynippononly Member Posts: 12,555
    since I do a lot of coasting to boost gas mileage, is that you can now just touch the "gas" pedal and you can coast along without the batteries recharging, but without any consequential drag on the wheels slowing the car down. It is very effective for long stretches of coasting. I don't recall exactly, but it seems that was not easy to do in the "classic" Prius. You were either powering the wheels or they were recharging the battery pack - it was hard to hit the midpoint where neither was happening (true coasting).

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • wwestwwest Member Posts: 10,706
    Wouldn't it be much better to simply say that the Prius gets its best MPG in comparison to other non-hybrid vehicles during travel that involves lots of unavoidable, necessary, "stop and go"?

    Traveling long distances wherein one does not accelerate dramatically, rarely stop at all, nor often need to prevent overspeeding the Prius would be at a definite disadvantage.

    All the extra weight of the electric motors and batteries with no functionality.

    That's why the highway cruising mileage is so poor in comparison.
  • hans000hans000 Member Posts: 19
    Keep it cool...

    According to '04 Prius manual and display, when the gas pedal lifted, the motor(s) applies _some_ regenerative braking to simulate conventional car's engine braking. Nothing for free: the car decelerates noticeably as if in 3rd gear of a stick shift car. To stop such braking I have apply a little gas peddle to stop energy flow on the display: the car would cruise a long way.

    When braking, the motor(s) applies _more_ regenerative braking. Someone actually measured the current on a '91 Prius. See the link below:
    http://www.lrz-uenchen.de/~u7224ac/www/measure.htm

    It's quite possible both electric motors do the braking. It's easy with electronics (inverter).

    The old Prius seems to use regenerative braking first and then (under heavy braking) apply the brake pads. It's said (never drove an old one personally) the transition was noticeable.

    The new one is seamless. My sales person (!) said that, in his training class, Toyota told them the brake was just applied as normal brake. That implies brake pads _in parallel with_ regerative braking.

    Now comes my question:
    when going downhill, should I use "B" or brake on '04? (I am asking fuel-economy-wise.) I don't feel ICE rev up in "B" while going down at 20MPH. Is it possible the "B" at 20MPH is just extra regenerative braking, not engine braking? On the old Prius I remember people suggested to avoid "B" for best fuel economy. Is this still true for '04?

    By the way, I highly recommend the following link for tech stuff:
    http://home.earthlink.net/~graham1/MyToyotaPrius/InitialContents.- htm
  • hans000hans000 Member Posts: 19
    I wouldn't say Prius highway MPG is poor, maybe less outstanding.

    Prius has the advantage of less powerful engine: it works within/near the efficient power band in highway cruise. Check this out:
    http://home.earthlink.net/~graham1/MyToyotaPrius/Understanding/In- ternalCombustion.htm

    Although the electric stuff adds weight, the transmission reduces the weight as a simple, fixed gear ratio one (see link below). Many thing mechanical in a conventional car is done electrically in Prius.

    One thing does hurt is that, instead of shifting gears, Prius uses a generator-motor pair to convert torque to RPM (as if in 5th gear)during highway cruise (see link below). I would guess the generator-motor pair is less efficient than a gearbox. (The plus side is that there is NO (zero, none) down shift delay. That makes the car fun to drive.)

    http://home.earthlink.net/~graham1/MyToyotaPrius/Understanding/Co- ntinuouslyVariableTransmission.htm

    ===wwest wrote:
    Traveling long distances wherein one does not accelerate dramatically, rarely stop at all, nor often need to prevent overspeeding the Prius would be at a definite disadvantage
  • john1701ajohn1701a Member Posts: 1,897
    > Cruising down the highway cannot create energy...even
    > going downhill is not creating energy...you are just
    > converting from potential to kinetic during downhill
    > motion...again NO FREE LUNCH.

    DUH! That's why it's called "RE"generating!

    I used the words "recapture" & "reclaimed" to clearly point out that the energy had already been consumed, an indication that FREE is not part of the equation. And in countless publications, it is very clearly pointed out what the percentage of recapture is. Never has 100% been mentioned. There is a cost. Recapture reduces it.

    These discussions keep becoming more and more amusing. You never know what the uninformed are going to come up with next.

    Watch the Multi-Display sometime while cruising down the highway. You'll witness how the engine flow stops and it switches to coming from the tires instead. It only lasts for a second or two. But since there isn't any such thing as an absolutely flat highway, it happens quite frequently. And every little bit makes a difference.

     
    > but Prius has an additional $7000 energy recovery system
    > over the cost of the ECHO.

    Ah! Starting to realize your original claim of $10000 more was off by a bit, eh? Anyway, it is still way off. If there was really that much of a price difference, how can you possibly explain why Corolla costs more than an Echo?

    JOHN
  • john1701ajohn1701a Member Posts: 1,897
    > Regenerative braking slows the vehicle down. If you intended
    > to stop or slow for some reason anyway that is all to the
    > good. But the use of regenerative braking while cruising
    > down the highway would simply defeat the purpose.

    Yes, completely ignoring the topic of discussion with alter its outcome. However, if I (once again) point out that using the brakes is not the only method, it may get us back on course.

    The topic was "regenerated energy".

    This occurs by the spinning of MG1 without using the engine. Prius has this ability. One way is by using the brakes. Another is slowing down by easing up on the throttle. Yet another is encountering a decline, which doesn't have to be a hill and will not cause deceleration.

    JOHN
  • SylviaSylvia Member Posts: 1,636
    Let's not duh! our way around the conversation...agree to disagree with civility.
  • bbridgewaterbbridgewater Member Posts: 9
    I am enjoying the seemingly elevated sensitivity of the Prius owners' MPG discussions. I am still waiting to take delivery of my backordered Prius, and look forward to getting even the "underperformance" of a high-30s mpg over the 12-17 I routinely get with my SUV!
  • djg4246djg4246 Member Posts: 2
    Looking for feedback on this. It's got me worried.

    I went to start my 16-days-old 2004 Prius after a day out in the near-zero, wind-whipped open parking garage last night in Watertown, Mass. Foot on the brake, gas in the tank (3 bars), press start and power button turns solid amber. Lights on dash light up as usual, all in the usual places, except no Ready Light. Gave it 5 minutes - let is sit like that - with foot on brake. Then, I tried to push the power button to turn it off. It would not turn off.

    After about 10 minutes or so, I called Toyota 24x7 roadside assistance. Operator couldn't help but put on the phone with a dealer in San Diego. Ran through the process a few more times and nothing. Held the brake pedal down and the power button for 20 seconds a few times and nothing.
    Dealer in Calif. said he thought I was stuck in a "neutral state."

    Now about 30 minutes, with the light still amber and car won't shut off or start, or go into any gear (still on "P") and no Ready lite. No noise coming from anywhere except for a grinding noise when I press on the brake (sometimes.) And, the headlights worked, so did fan or radio etc. (which I had off when trying to start the car.) With the dealer, I kept running through the START processes over and over, but nothing.

    Then, more out of frustration than anything (now at the 45 minute mark), I quickly pressed the green Park button off & on, did same to the Amber Power button all while pressing the foot brake on and off. And -- the car started!

    The dealer in Calif said he was not sure what freed it up. It it was a something frozen or a malfunction or something just stuck somewhere.

    Good thing it started. I didn't fancy leaving the car in "amber" while waiting for a tow truck. And once the tow truck showed up... actually what would it do???

    I drove it home without incident -- although there is no green light on the Power button. I thought that this green light was always on when the car was running. It didnt light again today while running. Is this normal?

    Anyway I have three questons before I head off to the dealer Monday a.m. with my story. (When I spoke to them today and they said they had a few calls about the cold and Prius '04s not starting quickly, but nothing like this.)

    Anyway, my questions before I hit the dealer on Monday to ask them to check codes or whatever they do:

    1. Any thoughts on the cause of the above -- and what is the proper cure next time?

    2. After all this, and only a couple of weeks with the car, I'm confused as to thinking that the power button was always green while driving? Or is there NO light on the power button while driving the car?

    3. If I could not have gotten the car to start... how would I have gotten it out of "amber"? I feared that it would remain that way until the battery just drained.

    Thanks for your help!

    Don, '04 Salsa BC, in chilly New England
  • m4ethm4eth Member Posts: 101
    I believe the preheated thermos can hold heat for three days and is used to warm the engine for starting...but if exposed to severe subtemps over days then you could easily loose the pre-heat function...not sure what effect this has on starting... but I would think this would be a concern?
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