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Toyota Prius (First Generation)



  • wwestwwest Posts: 10,706
    Over-inflating the tires will result in better MPG (less tire/roadbed friction) but poor braking and steering control due to less (contact patch) traction.
  • xcelxcel Posts: 1,025
    Hi Wwest:

    ___I believe the 04 Prius is using GY Integrity’s? I cannot speak for over inflation but the GY Integrity’s are rated for 44 #’s per the manufactures specifications. The question about what the differences are between braking and cornering is a good one but at what point are the tires pressures to high? Above the manufacturers spec? To low? Below the manufacturers spec? Just right? Toyota’s spec? I do know that 37 to 40 #’s in the GY Integrity’s as well as Mobil1 Synthetic in the 03 Corolla has given me an almost 20% increase in hwy mpg over and above what the EPA says the Corolla is rated for on the Hwy. Many Prius, HCH, and Insight owners have found similar pressures and higher works great for them as well with the OEM equipped LRR Bridgestone’s. The going tire pressure for the LRR Bridgestone’s from the Insighter's is 50 #’s and many swear by that pressure in the Insight forums. In fact, some have received 80,000 miles out of them at that pressure and have not received the outer edge wear problem many have experienced at 35 – 36 #’s or a more normal 30,000 miles before replacement as many Insight and former Prius owners have had to endure.

    ___Again, I can’t speak for safety or cornering because those 50 # Insighter’s are running well beyond the 44 # maximums of those particular LRR tires ratings but it works for them. 40 #’s in a set of GY Integrity’s is 10% below its rated maximum and most certainly helps as far as mileage is concerned ...

    ___Good Luck

    ___Wayne R. Gerdes
  • wwestwwest Posts: 10,706
    Automotive manufacturers know the approximate average weight of the vehicle so their pressure recommendations will likely be more "on target" than the tire manufacturer.

    Unless it's Ford trying to avoid high rollover calculations and thereby murder their Exporer owners.
  • wwestwwest Posts: 10,706
    Anyone know of an easy way to disable the electrics in cruise (60-70MPH) on the freeway?
  • john1701ajohn1701a Posts: 1,897
    > disable the electrics in cruise

    You can't. It's at the heart of the system, not an add-on. The power-split device will always do something electrically as a result.

    Most of the time while cruising, it is uses the excess torque created by running the engine at optimum RPM (which saves gas in itself) to recharge the battery-pack (which ultimately also saves gas). So disabling that would cause a loss in efficiency.

  • wwestwwest Posts: 10,706
    The only time I've driven the Prius any distance on the freeway was Seattle to Portland, maybe 170 miles, tops.

    It appeared to me that one of the causes of poor highway fuel economy vs city was that the system used the batteries for even slight power "boosts" at highway cruising speeds. And of course eventually had to recharge them the inefficient ICE method.

    It seemed to me that at cruising speeds the batteries should be brought "on", ONLY at WOT, when there is a clear(er) need for more HP than can be provided by the ICE alone.
  • john1701ajohn1701a Posts: 1,897
    Running the engine at optimum RPM, saves gas.

    Running the engine at the desired road speed would actually require the use of more gas, so that suggestion causes an efficiency loss.

    To achieve optimum RPM, the engine will actually increase spinning speed. Obviously you don't want that to result in an increase road speed, so the extra thrust is instead used to generate electricity for recharging.

    Also note that there is a clear MPG increase when you use the motor to maintain speed on a decline of any kind (not even enough to call a hill). Fuel is cut entirely from the engine and thrust is temporarily provided exclusive by electricity. So not taking advantage of that ability is an efficiency loss too.

  • wwestwwest Posts: 10,706
    Allows the ICE to run at it's most efficient at typical road speeds. The ONLY time the electrics increase efficiency is via regenerative braking.

    Using gasoline to charge batteries and then using those batteries to drive the wheels doubles the losses.

    Toyota is selling the public a "load of poles".

    For freeway use a supercharger or even a turbocharger would be a much more efficient method for getting more "go" from a small lightweight ICE such as the one in the Prius.

    Look at the Saab SVC, for instance.
  • wwestwwest Posts: 10,706
    Don't want to appear to be misleading.

    The use of batteries to store the energy recovered via regenerative braking for later use is an absolutely excellent idea, and Toyota should be applauded for bringing the Prius design to market.

    But using the batteries to boost HP at a time when the only recharge capability is the ICE is rather stupid IMMHO!

    And yes, the "system" has no way to predict when this circumstance exists, but I do!

    Give me an "electrics" OFF switch on my Prius that is automatically over-ridden at WOT and I'll give you better hwy MPG.
  • it's called N (Neutral) - no charging of the
    batteries, no charged pulled from the batteries.

    Then again, no power coming from the engine goes
    to the wheels either! ;-)

    what's to say that the most efficient (and least
    polluting) engine RPM isn't one that provides more
    power than the vehicle needs at that moment? The
    extra power is diverted to the batteries, for later
    use. (it's the only explanation I've seen for people
    who drive the hilly/mountainous route who get higher
    MPG than if they were to drive the flat route to
    the same place...)
  • john1701ajohn1701a Posts: 1,897
    > The CVT allows the ICE to run at it's most efficient
    > at typical road speeds.

    The factor you seem to be overlooking is that a highway is not perfectly flat, without any wind or turns, and has no other traffic. The constant influence of ever-changing small external factors isn't something that a CVT alone can rapidly respond to. But with an electric motor attached, it can.

    The optimum RPM takes those influences into account. And since the motor is spinning anyway, the responsiveness is nearly instananeous. Power can be diverted or created much faster than an engine-only design. So it is able to react to those numerous & frequent small changes, which results in a savings.

  • wwestwwest Posts: 10,706
    Say I'm in cruise control, 60MPH, going uphill, the engine speed needn't (should NEVER) change, just the throttle opening and the amount of power the engine produces at a given FIXED RPM.

    One could argue that at different throttle openings, power settings, the engine has differing optimum RPMs. In that case I'd still adjust the CVT rather than take the doubling of losses from the use of the batteries.

    For the pilots out there CVT is nothing more than a form of constant speed prop.

    Many years ago I got a speeding ticket going downhill on the eastside of Snoqualmie pass because I had wanted to see how high the MPG would indicate on the mileage computer. Placed the transmission in neutral and just as the computer reached 147MPG the radar tagged me at 77MPH. Limit was 55 then.

    In the Prius on cruise control much of that downhill (FREE) energy would have gone into the batteries in order to keep me closer to the cruise set speed.

    Again, regenerative power, power otherwise wasted, is the name of the game.
  • john1701ajohn1701a Posts: 1,897
    > One could argue that at different throttle openings

    That is a very DIRTY choice. And since reducing emissions is the primary purpose of Prius, not maximum efficiency, it gets put lower on the priority list.

    By the way... disabling the "electrics" would require the sacrifice of having Electric A/C, which provides a big boost in city efficiency... something many wouldn't be willing to give up.

  • wwestwwest Posts: 10,706
    I'm sure there is someplace in the system wherein a "switch" (hard, virtual??) could be placed to prevent the batteries from being used for a "driving" force.

    DIRTY choice....???

    I said that if a different throttle opening resulted in a different RPM need for optimum engine operation then I would adjust the CVT "gear ratio" such that the engine RPM could change without changing roadbed speed.

    Assuming your definition of optimum means lowest pollution level without unduly(~??) sacrificing MPG.

    Oh, I just realized that to my mind "optimum" means bringing all parameters into BALANCE.
  • I tried to buy a 2004 Prius this afternoon. I was working with the internet sales manager. He quoted me MSRP and said they would not take anything less. I had the blue book printout and I ask to see the dealer invoice. He said he had always worked from the blue book price and had never seen a dealer invoice before. He managed to get it from the sales manager and I started looking it over. I ask him was the dealer hold back percentage 2 or 3 percent. He said he didn't know and had never seen that disclosed anywhere before. I found there was not one but two hold back figures listed on the dealer invoice and pointed them out to the sales person. A $399.00 dealer hold back and a $199.00 finance hold back. Another interesting figure was a $495 advertising fee. This car came with the AM 7 option pack and the Z1 accessory pack. I was not interested in the Z1 pack but they said they would not throw it in at no cost. I said I wanted to check on financing options and they wanted me to feel out a credit form and do a credit check. I surprised them by having my credit score and credit report with me. They said they thought they could get me 3.9% interest rate but I had already qualified for Capital One E-loan. I do not believe they have sold one yet but this car has had 72 test miles put on it so far. I turned their offer down and said I needed to check a few other dealers. I began to walk out, the sales folks huddled a minute, but I could have swore I heard the sales manager say there was no way they could give me the price I wanted so I left. All I wanted was to have the Z1 pack free and either the $399 dealer hold back or the $495 advertising fee taken off MSRP.
  • wwestwwest Posts: 10,706
    Get a quote over the internet for the car equipped the way you want it FIRST. There are more customers than cars and if you're already on the dealer's tuff he's going to figure you're already "half" sold.
  • backybacky Twin CitiesPosts: 18,905
    To Pat... this is a bit confusing. This board is in the Sedans topic. But almost all of the recent discussion is on the '04 Prius, a hatchback. However, there is a separate board in the Hatchbacks topic on the '04 Prius, but it isn't called "Toyota Prius 2004+" to be consistent with other boards that start anew with a new model (like the board on the '04 Sienna), it's "2004 Prius - What do you think?".

    One way to make it real clear which board is covering what car is to call this one "Toyota Prius 1997-2003" and the one in the Hatchbacks topic "Toyota Prius 2004+". Just a suggestion.
  • patpat Posts: 10,421
    Excellent point, backy - thanks.
  • Until recently I have enjoyed getting 42-52 mpgs in the 2.5 years that I owned my 2001 Prius. However, my check engine light came on at around 29,000 miles and I am currently only getting around 36 mpg!!! When I took it to the dealer for the check engine light problem, they replaced a "Pipe Assy, Exhaust($1487), Actuator Assy, w.Bra ($134), Gaskets, and an Oxygen sensor ($125). Since the installation of those new parts (which were covered under warranty) the gas consumption has been in the mid-30's. UGH!! When I took it back to the dealer, they put it on a computer and reported "they could find nothing wrong" and suggested I keep a log of my own, rather than depend on the computer read-out. However, I know something is terribly wrong because just riding up a slight hill, (that I ride up each and every day to my house), I lose a mile per gallon whereas before all this started I only used to lose .2 of mile per gallon driving up the same hill. Also, I am only getting about 350 miles between fill-ups. I used to get well over 400 miles. Has anyone else experienced this problem with their Prius? The dealer seems not to be too interested in my problem. I wonder if Toyota would be more interested?
  • xcelxcel Posts: 1,025
    Hi Jannendave:

    ___In many cases, once the EGR valve starts to go, fuel mileage and performance will drop hard. Just a thought as to what could be causing your lower mileage possibly? Cold weather shouldn’t hit your Prius that hard as this as you have probably already surmised.

    ___Good Luck

    ___Wayne R. Gerdes
  • nofeernofeer Posts: 381
    a car mag did the math, it would take 150k miles before a hybrid would pay for itself. they don't make economic sense, but they must be sold so the technology can filter to larger vehicles. i feel the future is diesel, if we could only get the low sulfer fuel. the difference between a golf jetta diesel and the prius isn't very much, but the tech is cheaper. and people are very cost sensitive. then they can introduce a diesel hybrid
  • backybacky Twin CitiesPosts: 18,905
    What was the car mag's basis for comparison to the hybrid? That would make a big impact on when the hybrid "pays for itself." If they are comparing to a compact like a Corolla or even an Elantra, I could see where they would conclude that the payoff comes after 150k miles. But if they are comparing to larger, more expensive vehichles like midsized cars, minivans, or SUVs, then the payoff would come much sooner.
  • I am in the process of purchasing a used 2001 Prius from an individual. Her Toyota dealership provided the repair record, but refuses to look the car over for me (I'll pay for it.) Another dealership also won't do it. AAA doesn't have diagnostic equipment for hybrids yet. The seller is concerned about taking the car to a private mechanic that neither of us knows. She's concerned they'll mess up the sensitive hybrid system. The prices is good, but I need to have a 3rd party check the car out before finalizing the deal. Can anyone recommend a reliable, honest, proficient mechanic w/ Prius experience in the East Bay (near San Francisco), preferably Walnut Creek/Concord vicinity?
  • Hi All,

    I'm considering buying a 2001 Prius for my lengthy daily commute. Five days a week I drive 120 miles round trip to my place of employment. The miles are all on the interstate and it is not an exceptionally hilly route. My speed of travel is generally 70 mph. Would you Prius owners recommend at 2001 Prius for this commute? Any idea what sort of gas mileage I might expect under these conditions?

    Any advice or opinions appreciated.

  • bigfrogbigfrog Posts: 27
    I thought prius had free service for life my mother in law has one her dealer is telling her no anyone one have any doc's on this??
  • eheadingeheading Posts: 26
    My 2003 Prius has free service for 3 years. Everything that's in the owner's manual for service gets done for the 3 years. It is a handy little addition.

    Ed Headington
  • gagricegagrice San DiegoPosts: 31,077
    I was reading where Toyota can void your warranty if you leave your Prius parked for more than 2 weeks at a time. That would never work for me I park my vehicle at the airport and am gone 3 to 5 weeks at a time working. Has this gotten corrected in the newer Prius models?
  • eheadingeheading Posts: 26
    Can't speak for leaving a car at an airport. We do leave our car for several months at a time. At the advice of our dealer, we disconnect the 12V battery from the car (with a knife switch) and keep the 12V battery on a trickle charger. When we return home, we reconnect the battery, start up the car, and away we go. I've never yet seen any effect on the nickel-metal-hydride batteries at all.

    Leaving the car without the charger, I just can't make any comment. We've never tried that, however I would doubt if it would be a serious problem.

    Ed Headington
  • midnightcowboymidnightcowboy Posts: 1,978
    The 12 volt battery is just a backup and is never used to start the car unless the Hybrid Nickel-Metal-Hydride batteries are discharged. It sounds to me like you are making work out of work. Because once you start up the car via the hybrid battery it will recharge any drainage of the 12 volt back-up battery. If you don't believe me disconnect your 12 volt battery and voila you car will still start. Hopefully you have a big enough knife switch to handle the current on the back-up battery should you ever need it. What do you do about the discharge of your nickel-metal-hydride battery ? If they are so discahrged they won't start the car, then they are probably into the "deep discharge" state that significantly shortens their life. But I gues if you can afford to leave your car for months at a time, you don't use a car that often and maybe it won't matter.
  • tempusvntempusvn Posts: 119
    >The 12 volt battery is just a backup and is never used to start the car unless the Hybrid Nickel-Metal-Hydride batteries are discharged.

    Not quite. The 12 Volt battery keeps the computers alive while the car is off, so it can respond to your request for the Traction Battery to start the motor. The 12V cannot start the ICE, because one of the MGs is really the starter, and the 12V can't spin it, and isn't connected to it anyway.

    >Because once you start up the car via the hybrid battery it will recharge any drainage of the 12 volt back-up battery.

    Correct, if you can get the car started. If not you have to jump the 12V.

    >If you don't believe me disconnect your 12 volt battery and voila you car will still start.

    If you disconnect the 12V battery, the car is dead as a doornail. Plus, you lose all your history and pre-sets.

    >What do you do about the discharge of your nickel-metal-hydride battery ? If they are so discahrged they won't start the car, then they are probably into the "deep discharge" state that significantly shortens their life.

    Correct, if the NIMH battery is really drained, the life may be shortened, but they can possibly be recharged. However, it takes a special Traction Battery Recharger that the Service Centers have.

    If you're going to leave the car for a long time you can:

    1) Disconnect the 12V, but you must reconnect it before starting the car, and you lose all your settings/history.

    2) Have someone come by every week or so and just turn the car on for a half hour. The Traction Battery and ICE will top off the 12V. Have to make sure it's really "Ready" on - not just IGN on.

    3) Hook up a maintenance charger. This is NOT a trickle charger. A trickle charger runs all the time, and can (risk, not certainty) overcharge and damage the 12V. a maintenance charger monitors the voltage across the battery and only charges when it begins to get low, and only as much as needed. They cost a bit more than trickle chargers, but not exorbitant. If you have a maintenance charger running, you can leave the 12V connected and not lose any puter settings. Some people have even wired in connectors to allow them to just plug it in.
This discussion has been closed.