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Toyota Prius



  • I have seen pictures of pre-delivery Prius from John and others and noticed that the rear bumper spoiler (black plastic) had not been installed. I have also looked at the PDF file for dealer pre-delivery prep work and it includes the installation of this spoiler. My question is: does anyone know if this spoiler is really neccessary? my personal opinion is that the Prius looks better without this spoiler. I am considering leaving this spoiler off prior to taking delivery and dealer prep. This may be a "drag coefficient" issues much like the plastic rings around the wheels. Hmmm...
  • john1701ajohn1701a Posts: 1,897
    > Using the ICE to recharge the batteries for additional
    > use will always result in a NET LOSS versus just using
    > only the ICE.

    THERE IS A LOSS, but it is NOT net. There really is a savings.

    Electric motors are more efficient than combustion engines. (That is not a topic for debate, it is a very well proven fact.) The point of the hybrid design is to be able to exploit that by MINIMIZING the loss circumstances. By reducing them as much as possible, you get greater efficiency than with a combustion engine alone.

    > Someone stated earlier that the HSD system would use
    > regenerative braking to recharge the batteries during
    > simple coasting

    Your misconception comes from the words "braking" and "regeneration". In reality, neither is accurate.

    HSD (and THS) use a "GENERATION" system. Whenever there is excess thrust, which occurs mostly when the engine is propeling the vehicle not when braking, electricity is created. Remember, the CVT intentionally creates this situation. Touching the brake is not required. The excess thrust is automatically detected.

  • drmpdrmp Posts: 187
    > Using the ICE to recharge the batteries for additional
    > use will always result in a NET LOSS versus just using
    > only the ICE.

    On the prius, stop-&-go city driving the engine runs and idle while charging the batteries and also recycle energy from regenerative braking. Engine shuts off when battery is fully charged. while engine is running, it also provide additional thrust to the wheels.

    On conventional car, the engine runs and idle even when not needed.
  • wwestwwest Posts: 10,706
    Absent brake application as a signal, EXCESS THRUST can only be determined by looking through MY EYES at what lies ahead and into MY MIND for my future (immediate) intentions.

    Automakers have been working FOREVER to reduce the drag coefficient and now you're trying to tell me they're readily adding it back in by charging the batteries via regenerative braking during "coasting".

    Sorry, can't buy that particular load of poles.
  • Test drove the '04 Prius couple of days ago. Handles very well, accelarates well. Seems to be a wee bit short on trunk space.

    What's with the options packaging? Is is the "market demand" effect? I wanted everything on the list except for the NAV since it has very little use for me. Turns out that's not possible, at least currently. NAV jacks up the price by about $2-3K! That's rather steep for something that I don't really want/need. Any ideas if this situation is going to change, i.e. be able to get a la carte options?
  • antzantz Posts: 13
    Hi All,

    Is there a button for forced the vehicle to be fully electric? I thought I've read some member was saying that there is such a feature? But I can't find it on my manual!

  • john1701ajohn1701a Posts: 1,897
    > EXCESS THRUST can only be determined by looking
    > through MY EYES

    The hybrid system creates it, NOT the driver. Perhaps that is the basis of your misunderstanding.

    How this design works can easily be cleared up by simply watching the Multi-Display while taking a test-drive.

  • john1701ajohn1701a Posts: 1,897
    It's really a "maximize stealth" button. "EV" is quite misleading.

    That particular feature is not available in the United States, due to regulation issues.

    Stealth still works here, it's just not maximized. But the performance is definitely improved from the classic model. So there's hardly much of a loss.

    Technically, the system could still be retrofit later on with that button. But currently, no one has figured out what it would take. Perhaps, once those dang regulations are dealt with, Toyota will offer an upgrade kit like they did for cruise-control.

  • wwestwwest Posts: 10,706

    NET LOSS...

    Ever notice that when charging or discharging batteries they tend to heat up? That's because ALL batteries have an internal resistance to electrical current flow. Try to charge a battery too fast and it will overheat and oftentimes explode.

    Same thing with discharging too rapidly.

    Look at it this way.

    Say I can use the ICE to run the generator which in turn powers the electric motor and that is used to drive the wheels. We just decribed a diesel/elect railroad engine by the way.

    Now put the Prius set of batteries in the system, I lose energy, via the battery resistance, both in the charge path and in the discharge path.

    The net loss can be really serious as is indicated by the Prius' poor hwy MPG. On the highway the batteries become nothing more or less than a supercharger with all the losses of same.

    Oh, and one of the referenced articles states the Atkinson cycle engines (Prius uses the Miller cycle modification of Atkinson) are hardly ever viable absent a supercharger. In the Prius the electric motor/battery combination serves as THAT supercharger.
  • On an instantaneous basis, it is ALWAYS less efficient to use electric drive than the ICE directly, since there are the ADDITIONAL losses of the generator, battery, drive controller and motor. ALL energy ultimately comes from gasoline (baring a one way trip from Denver to death Valley, or other net downhill, or a tailwind). Cycle efficiency is a different matter, however, and the designer must choose compromises based on an assumed driving cycle. Electric-only operation may contribute to net cycle efficiency to the extent that it reduces the number of ICE starts and/or allows the ICE to generate under more efficient operating conditions (i.e. the improvement in ICE efficiency is greater than the electric drive losses for a given operating condition). Confounding this is the need to reduce emissions and/or accelerate and/or climb mountains and/or whatever.

    Whether a particular operating mode, under specific conditions optimizes a particular parameter within a particular driving cycle is a question that only Toyota can answer, anecdotal evidence notwithstanding. Consequently Toyota's program is the best resource that you have to determine whether electric only operation is beneficial, so why would you want to maximize it?
  • wwestwwest Posts: 10,706
    First, I didn't say the driver did.

    What I said was that I'm the only one to see, and I'm the ONLY decision maker, as to whether or not I wish the car to be slowing down.

    If the hybrid system suddenly, or even "seamlessly", decides to throw in a little regenerative effort I would most likely suspect that a head wind just came up and I need to apply more throttle to maintain my speed....

    If I'm going downhill and lift my foot from the throttle to conserve fuel and the system starts applying the "brakes" my instincts will be to get back on the gas. Even if I don't get back on the gas immediately then I will still need to do that earlier than otherwise due to the increased "drag" of the regenerative effort.

    Like a heavilly loaded trucker coasting, speeding, downhill to conserve fuel but then throwing a dragchute out.

    On the other hand a light foot on the brake pedal (or in "cruise") to maintain a set speed downhill and the system using that as a signal to charge the batteries for "boost" on the uphill pull makes a lot of sense.
  • john1701ajohn1701a Posts: 1,897
    > The net loss can be really serious as is indicated
    > by the Prius' poor hwy MPG

    A 51 MPG highway rating is poor?

    No other gasoline powered vehicle that size can compete with efficiency so high. Since the end result is *BETTER*, it is a *GAIN*. How can you claim a net loss?

  • wwestwwest Posts: 10,706
    I would be willing to bet you a brand new 04 Prius that I can BEAT the hwy mileage of any 04 Prius in that same Prius if I could prevent the batteries from being needlessly used on a run from Seattle to Portland.

    Watching the dash "gauges" it was my experience that no matter how lightly I feathered the increase in throttle position the electrics would come FULLY on line. I was willing to settle for a slow acceleration rate using just the ICE but the system wouldn't let me settle for that. The result was about 30 to 40 needless discharge/charge cycles in 150 miles.

    Yes, 51 MPG is pretty damn good. But if one could avoid needlessly discharging (supercharging the "weak" engine) and then recharging the batteries in a continuous cycle for a 150 mile reasonably flat freeway drive the mileage would be even better.
  • wwestwwest Posts: 10,706
    I have read all three references, all good reads, especially the latter, but I can find no statement implying the batteries are automatically charged during coasting.

    Would you mind directing me more explicitly to same?
  • john1701ajohn1701a Posts: 1,897
    > ...flat freeway drive the mileage would be even better.

    That has absolutely, positively nothing to do with a "net loss".

    It is still a gain no matter how you analyze it. What did I miss?

  • wwest,

    It works a similar way in the Civic hybrid. Lifting off the gas causes the regen feature to kick in.

    To maximize opportunities to recharge the batteries, I guess the computers assume that when you're not on the gas, you don't need thrust, so that spinning drive shaft can be used to turn the generator (electric motor). I use it all the time to maximize charging.

  • wwestwwest Posts: 10,706
    I was not referring to the "overall" design or execution of the Prius design, only to the detail of the NET LOSS resulting from the needless discharging of the batteries resulting in the losses via the use of the ICE for recharging.
  • john1701ajohn1701a Posts: 1,897
    Quite a number of times now, definitions of words have changed as discussions continue. No hard feelings on this side. I've grown used to it.

    For our next topic, how about discussion winter efficiency? Lots and lots of people aren't aware of those cold weather factors that cause MPG to drop.

  • wwestwwest Posts: 10,706

    You "restated" my position on NET LOSS so explicity in post 1096 that I see no way it could have been misunderstood to be more "global" than I intended.
  • Graham's site pretty well describes the charging
    while coasting.

    You can really notice the difference between the
    regenerative braking while coasting, vs. no
    regenerative braking, by throwing the Prius into
    Neutral while coasting. Instead of slowly slowing down,
    you just sort of glide along. Unfortunately, by
    going into Neutral, the battery no longer gets
  • In a normal car, any excess power from the ICE
    that isn't used for motive force is wasted. (Think
    about coasting or going downhill - the engine isn't
    doing much work to keep you going...)

    In a Prius, the eCVT keeps the ICE at the most
    efficient (cleanest) RPM. In some cases, there is
    more power coming from the engine than what is
    needed to move the car (uphills, usually), and this
    excess power is routed to charging the battery, or
    the electric motor.

    Strange, but usually a Prius gets better MPG going
    through hills than if it took the flatland route!
  • I placed an order for a 2004 Prius in mid-October with a Fairfield County CT dealer. Yesterday I spoke with the salesman, who said that I was 15th on their order list and they anticipated getting 1 or 2 a month starting this month. And only two option packages - everything or almost nothing. When I go online to for Ft. Lauderdale, where my daughter lives, the availability list goes on for pages, with lots of different option packages. I could cancel my CT order, order the car in Florida and ask her to drive it north, and maybe I'd even have some bargaining power on price. Does anyone have any thoughts on whether this makes sense? And why is there such a demand - supply imbalance?
  • john1701ajohn1701a Posts: 1,897
    I've grown tired of constantly having my words twisted here. That doesn't happen elsewhere.

    Those that are interested in assistance with Prius know where to find me. And I'd much rather help them than just put out all the fires you keep setting.


  • wwestwwest Posts: 10,706
    coming from the engine than is what needed to move the car (uphills, usually)....

    Why would the engine produce more power, using MORE fuel, than is required to move the vehicle, especially uphill? I would think, assuming the batteries have some reserve left, this would be a very important time to use the batteries to boost the net output power and conserve fuel.

    As a matter of fact that's the exact way my 03 seems to work. I'll have to pay more attention now, but I don't think I've EVER seen the batteries being charged in this circumstance. Absent starting out virtually fully discharged, maybe.
  • wwestwwest Posts: 10,706
    Without admitting that it actually does....

    How or why is it an advantage to use regenerative braking during "coasting" (no throttle or brake application) to recharge the batteries?

    Without this "braking" (however slight) the car would coast farther and thereby use less fuel overall.
  • john1701ajohn1701a Posts: 1,897
    > Without this "braking" (however slight) the car would coast
    > farther and thereby use less fuel overall.

    The primary purpose of HSD is to REDUCE SMOG-FORMING EMISSIONS.

    Since using less fuel is secondary, opportunities to do save are sometimes not taken for the sake of being CLEANER OVERALL.

  • I have had the '04 prius in my garage for 1 week. Averaged 46.3 mpg over first 400 miles, without trying. I love this car. Handles better and rides more smoothly than old Prius (my daughter has an '01). The fold down rear seats were a necessity for me. The blue is a very nice shade, was kind of hard to tell exactly what you were going to get from the web site. I got the first one from my dealer. My only complaint to date is the faint green line on the windshield at night from reflections from the speedometer display- any suggestions? I haven't tried to create a "blocker" about the display yet.
  • seem well pleased with their new Prius, as it should be.

    I am eager to see how it compares to other vehicles when there are independent test reports available.
  • lsinclsinc Posts: 270
    My husband and I are considering purchasing an '04 Prius sometime in the future. Currently my husband commutes 350 miles in 5 days and we are looking for fuel economy. We also need a car that is reliable and good in snow. Can anyone give me information on

    1. Fuel ecomony ratings
    2. Overall Reliability
    3. Handling in rain and snow


  • Masshockey...I've post this issue previously and from other owners, all you have to do is turn down the dimmer switch/wheel to the left of your steering wheel. This should take away the glare. Happy driving. Tony.
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