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idle milage question

Discussion in 'Gen 2 Prius Fuel Economy' started by SureValla, Dec 3, 2007.

  1. SureValla

    SureValla Member

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    Everyday I drive 25 min to work where I have to get out of my car, go sign into a guard booth and get a pass. I then get back in my car and drive for 5 more min to the building I work in.

    My question is during this time when I am in the guard booth is it best to keep my car running or shut it off and turn it back on 2 min later to maximize my milage?
     
  2. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    To me, it depends on what the car is doing during that time. Personally, I drive ~25 miles to work myself. I know in the summer that after such a drive, I could leave the car powered up and it would sit without turning on the ICE for five minutes. In fact, I was pulled over once close to work and for those ten minutes the engine didn't come on once.

    If that's the case, I would say that it's safe to just leave it on. Unless, of course, there's something about where you work that would make it "unsafe" to leave an unattended car running.
     
  3. a priori

    a priori Canonus Curiosus

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    Keep it on!

    If you've been running for that long, you're already running in S4, and there is no reason to turn off the car unless you are concerned someone may drive away with it or take something of value from the cabin. (EVen so, I think you can lock the car by using the actual key in the driver's door lock.)

    If you turn off the car, you'll be forced through an ICE run after you turn the car back on. Just make certain you turn off the A/C and/or heat, otherwise you'll have the ICE turn on just to keep the interior managed. With that waste of fuel, you are doing more harm than good by leaving the car on.

    I'm very comfortable leaving the car in Ready mode for as much as 5 minutes (even if I've been driving for a shorter period of time).
     
  4. patsparks

    patsparks An Aussie perspective

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    Why not hit the power button rather than the park button? Then your not wasting power from your traction battery running control computers, radio etc. Your car will be more secure with the engine off and the key fob out too.
     
  5. Aces

    Aces Member

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    Recently I realized that the car will keep running when the SKS Key is outside the car. Does anyone know if there's a limit to how far before it would shut it down? If it doesn't care, you could accidentally leave your key outside the car and drive off. And once you'd powered it off, you'd be stuck wouldn't you? :confused:
     
  6. JimN

    JimN Let the games begin!

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    If the fob is "far enough" away the car will start to beep. It will continue to run until powered off.
     
  7. Danny Hamilton

    Danny Hamilton Active Member

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    I'm not positive but I believe the limit is somewhere around 12,500 miles. I don't think you can get much further than this (on a great circle path over the surface of the earth) from the fob with the car on (the straight line distance is likely to be a bit less).

    Of course, to turn the car on in the first place, you need to have the fob in the car. You would then need to remove it from the car before driving away. It has happened to a few people who have posted here at PriusChat, but I don't think it is common.

    Yes, if you drive away without the fob, you will be stuck if you turn the car off (until someone can bring the fob to you or you to the fob).
     
  8. Aces

    Aces Member

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    Thanks for the replies. I always leave my key-chain hooked to my belt. So it'd be rare to run into this situation. BUT, the morning in question, I'd realized I forgot something in the house and went inside to get it, using my keys to unlock the door to the house. In that situation, I was running late and a bit flustered. If I'd left the key in the house by accident, It could have been a REALLY bad day. It's good to know about the beep!
     
  9. philmcneal

    philmcneal Taxi!

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    i would say no!

    when you restart the prius, for some odd reason the prius likes to use way more gas than it usually does to confirm that your indeed going to drive the prius (DUH). so it burns at a rate of 3.0L-2.6L per hour just for 10-15 seconds or so in a rich fuel mode to ensure the cataylic converter is hot and toasty ready to clease any emissions from your driving habits!

    if your engine was cold, that 10-15 seconds would translate towards the 40sec-1 minute period. and yes this is the same mode that forces the car to be propelled by electricity only while the enigine is "doing its thing"

    it may seem small to you, but it adds up, i rather idle 2 minutes at a rate of 400watts/hr rather than burning 3 liters in 15 seconds, to each and their own.
     
  10. patsparks

    patsparks An Aussie perspective

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    That is really a maximum of 0..0125 Litres in 15 seconds.
    I have never seen evidence or heard this, if my engine is warm and I have only been out of the car a few minutes the ICE doesn't start until my rate of acceleration requires it to.

    Aces,
    Do you need a retractable key tether?
     
  11. JimboK

    JimboK One owner, low mileage

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    Could it be that those sold "down under" are designed that way?

    This has been described numerous times, at least by those with the US Prius. In my experience, it doesn't matter how warm the ICE is upon shutdown or how short the shutdown time is. The ICE will insist on running again on the next power-up regardless of the power needs. The current draw while powered on with no accessories running is minimal, about 600-700 mA. So unless it's unsafe, I generally choose to leave it on with stops of less than 10 minutes.
     
  12. philmcneal

    philmcneal Taxi!

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    all i know is the act is under the effect for emissions, as to why your car you get to power on/off/on and then being able to be in ev mode right away really shows at least a) they fixed it or b) your emissions laws differ from the north american standards.

    you think that 10 - 15 seconds make no differences, but it adds up, i also just figured out that for you guys its summer so maybe the algoritihm is different but I do remember having the engine above 70 degrees C in my summer and it still had to "do its thing".

    as for jimbok that's some tiny ampage for idling! you lucky US bums don't require day time running lights, it puts our idle at a whopping 400 watts/hr and if i use the ebrake to disable DRL i can get it down to 200 watt/hr idling.