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Car not really off.

Discussion in 'Gen 2 Prius Fuel Economy' started by ZooPrius, Feb 11, 2009.

  1. ZooPrius

    ZooPrius New Member

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    I was reading the worst tank ever post and thought I would be seeing mine this week. Even with a bunch of short (10 minute) trips in sub zero temperatures my worst is 36.5 MPG. This week with temps hovering in the 30-40 range it looks like I would have made about 45-50 MPG except that I parked for about 3 hours last night and when I came back to my car I was surprised to find that the car was on and running!!! The gas guage was down one or two blocks and my milage was down from 47.9 to 45.0 MPG at 300+ miles. I am pretty sure I hit the power button to turn it off before I left the car. I did reopen the door after I had locked it to put a parking lot ticket on the dash. The car was silent and I am pretty sure there were no monitor or dash lights on. Clearly it was not running the entire time or the milage and gas tank would have been worse.

    Any one know why this might happen other than maybe I am just a clod who forgot to turn off his car?
    You would think Toyota might have some automatic turnoff when it is on and not running for three hours?

    Fortunately the car was nice and warmed up so when I drove home I was in the 100 MPG range most of the time and got my total milage close to where it was before.
     
    #1 ZooPrius, Feb 11, 2009
  2. firepa63

    firepa63 Former Prius Owner

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    As Homer Simpson would say ... Dooh!
     
    #2 firepa63, Feb 11, 2009
  3. Tideland Prius

    Tideland Prius Moderator of the North
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    Do you remember hearing any beeps when you closed the door?

    It's also possible you didn't see the speedo because of the angle (you said you were putting the parking receipt on the dash)
     
    #3 Tideland Prius, Feb 11, 2009
  4. richard schumacher

    richard schumacher shortbus driver

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    Of course it was running the entire time. It didn't start itself after you left it. It just doesn't take a lot of fuel to keep itself warmed up. It's very easy for people to make mistakes when a routine has been broken by some surprise, in this case dealing with the parking ticket.
     
    #4 richard schumacher, Feb 11, 2009
  5. a priori

    a priori Canonus Curiosus

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    Chances are pretty good you simply thought you pushed the Power button, but instead pressed Park.

    Someone with a better memory can help me out on this one: You also may have pushed the Power button twice in succession. If you do it very quickly, you may get into great trouble by leaving it in ACC, as opposed to READY mode. It has happened to many of us!

    I once left mine in Ready overnight in the garage. It was "On" for more than 12 hours, but it used very little gasoline!
     
    #5 a priori, Feb 12, 2009
  6. dropkin

    dropkin Junior Member

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    You wouldn't be the first. As an aide, I always had the radio on so I would know for 100% that I had turned off the engine. It would be nice if there was a shutdown sound... my PC does it... why not my car? :)
     
    #6 dropkin, Feb 12, 2009
  7. Mike Dimmick

    Mike Dimmick Active Member

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    This is why I prefer non-Smart Key (we don't even get it in the UK) - you have to turn off in order to take the key out of the dash.

    The 2010 car seems to have proximity RFID even for non-'Smart Key' - there is no slot. I suspect this will lead to more not-really-off problems.
     
    #7 Mike Dimmick, Feb 12, 2009
  8. ZooPrius

    ZooPrius New Member

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    I thought there should be beeps if you walk away from the car while it was on. I have intentionally done that before and there were beeps. This time I am pretty sure I would have heard a beep if it were beeping but I didn't hear any.

    Also I was not distracted. It was not a surprise parking ticket, it was a receipt for parking in the lot.

    The angle might have made it hard to see the dash and the monitor but it was evening and getting dark out so I would think at least the monitor would have lit up the cabin.

    I suppose I could have pushed the power button twice but wouldn't the car still beep while I was walking away.

    I like the radio idea and will use that from now on.

    On a semi-related note. Safety issues aside is it better from a gas milage stand point to keep the car on with the parking break on rather than shut it off for a few minutes if you are just going to be stopped for a few minutes? Does this eliminate the automatic ICE start up in the first five minutes?
     
    #8 ZooPrius, Feb 12, 2009
  9. richard schumacher

    richard schumacher shortbus driver

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    Always lock the car. In this case it would have given a long beep of warning.
     
    #9 richard schumacher, Feb 12, 2009
  10. a priori

    a priori Canonus Curiosus

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    It may not surprise you this has been the topic of more than one thread (or at least has been part of the discussion in several threads).

    Looking at it strictly from the effect on mileage? You must account for the temp of the engine, the state of charge of the battery, the time you'll be gone and the initial driving you'll do once you get back in the car. I think the last of these is the one with the greatest impact, because if you know you'll need to step on the gas right away, and for more than just ten seconds or so, then it likely makes no sense to leave the car in Ready.

    If the SOC on the battery is relatively low, then nearly any action once you return will require ICE use right away. Likewise, if the car is still cold (and pre-stage 4), you'll be requiring ICE use anyway.

    I had been one to leave the car on, regularly, when going into the convenience store or making any stop for less than 4 or 5 minutes. Now, I'm thinking it really isn't going to make much of a change in overall mileage, but it could be pretty disastrous from a physical safety or economic well-being perspective: I don't want someone just driving away in my car or reaching in to take something.
     
    #10 a priori, Feb 12, 2009
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