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Question re: driving style

Discussion in 'Gen 2 Prius Main Forum' started by orenf, Apr 18, 2008.

  1. orenf

    orenf New Member

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    When I leave my street I can choose between (a) making a left turn at a stop sign, onto a busy road or (b) waiting at a light.

    Either way, 9 out of 10 times I start my car, and in 30 seconds or so I come to a full stop, sometimes for 3-4 minutes. Needless to say, since the car is cold, the engine is always on, with the resulting drop in MPG.

    Now, I'm not looking to somehow "bypass" the cold start phase, but I can't help wondering - am I not better off simply turning the engine off when I stop, and then restarting the car as soon as I can go (may be an issue for the stop sign, not so for the traffic light)? I'm simply postponing the warm-up cycle until I'm actually covering some distance, so that the M in MPG > 0 (which is the case when in full stop). Does that make sense (or any MPG difference)?

    --- Oren
     
    #1 orenf, Apr 18, 2008
  2. morpheusx

    morpheusx Professor Chaos

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    Try turning off your climate control when you leave your house for that warming up period, the engine may decide to shut off if you are at the light for more then 3 - 5 seconds, even if its not warmed up yet.
     
    #2 morpheusx, Apr 18, 2008
  3. ForTheGlory

    ForTheGlory New Member

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    Seems like your situation is crying out for an EV Mod switch. It seems to me to be extremely dangerous (and probably illegal) to completely turn off your car at a traffic light. But with the EV Mod, you could force your engine to stay off (provided that you have the correct battery SOC, don't demand too much power, etc).
     
    #3 ForTheGlory, Apr 18, 2008
  4. efusco

    efusco Moderator Emeritus
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    Let it run. I agree with reducing or minimizing the climate control use...try AC off, auto-off, and temp to Max cool (basically just a vent setting). Keep your foot firmly on the brake pedal. The ICE will probably quickly shut down, but in cooler weather it may, well, run the entire time as it warms up. And that's actually ideal. It's better for it to warm up through S1 esp., in a very low demand state like that.

    Yea, it's ugly to look at that initial MPG hit, but if you get warmed up during that time you'll recover it more quickly over the same piece of road that you otherwise would continue to lose FE.

    Buy shutting down you'll just force the car to go through S1 a second time...no advantage. You could consider an EV button/mod to force the ICE off, but I wouldn't.

    Finally, and truly the best fuel economy option for you, would be to install an engine block heater. This will pre-heat the ICE to around 130F before you even start. By the time you get to your stop light you'll probably already be in S3 and possibly even S4 depending upon the distance and weather.
     
    #4 efusco, Apr 18, 2008
  5. JimboK

    JimboK One owner, low mileage

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    (Had this mostly composed before realizing that Evan beat me to it. ;))

    Before the EV mod I would recommend an engine block heater. The EV mod may create some warranty issues, requires active driver input, and may hurt fuel economy if misused. Should be no warranty issues with the EBH (Toyota Canada sells them), it requires only that it be plugged in a few hours before startup, and will only help fuel economy. It will shorten the initial warmup stage to as little as 30 seconds or so in warmer weather.
     
    #5 JimboK, Apr 18, 2008
  6. morpheusx

    morpheusx Professor Chaos

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    Take his advice ever since he steered me away from driving onto the highway after work (less then 1 mile from my work parking lot) and letting it warmup by just driving it through a nice little neighborhood at 25 MPH to the next onramp for the highway, my MPG have soared on my daily route. (half way between the 25 and 50 bar on the first 5 minutes).
     
    #6 morpheusx, Apr 18, 2008
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