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How does the EV mod affect your mileage?

Discussion in 'Gen 2 Prius Fuel Economy' started by stomsf, Nov 12, 2007.

  1. stomsf

    stomsf New Member

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    Just wondering for those who have/use the EV mod -- do you see a marked improvement in your fuel economy?
     
  2. seasalsa

    seasalsa Active Member

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    <div class='quotetop'>QUOTE(stomsf @ Nov 12 2007, 04:04 PM) [snapback]538619[/snapback]</div>
    No. It is nice to have at times but no marked improvement.
     
  3. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    The EV button is not designed to boost your mileage. Period.

    In fact, if used improperly, you will most definitely ruin your mileage. Here's an example: let's say you're cruising along at 25 MPH. Seems like a great time to use the EV, right? Let's hit it. Now we're zipping along all stealthy like. Uh oh, we've depleted the battery and now the EV has disengaged. Here comes a stop light that just turned red. We have to stop. And wait. And all the while the engine is running. Why? Because it's trying to recharge the battery that we just depleted. Okay, the light's red now. Better, right? Wrong. Now that we're accelerating with a depleted battery, our instant mileage is even worse.

    Of course, that scenario will play out for about a couple miles until the battery gets back up to about 50% SoC. At which time we punch the EV button again. D'oh!
     
  4. Tideland Prius

    Tideland Prius Moderator of the North
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    Rather than boost mileage, it's meant to curb mileage loss. IOW, instead of losing x mpg, you'll probably lose x-y mpg.
     
  5. blamy

    blamy Member

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    When I have green bars on the battery indicator and at a stop light I use the EV mode. Feels good to do it but I do not see any real gas mileage increase.
     
  6. 9G-man

    9G-man Senior Member

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    Short answer, little-if-any MPG increase, and very possible MPG reduction.

    Another way to look at it, there is often a big opportunity cost to using the EV switch. Liberal use of the EV switch will often end up hurting overall MPG because it robs you of future ICE off, stealth and glide opportunities that would have given a better mileage return. (having lowered battery SOC, and forcing ICE on/increasing it's output.)

    Here is another example. I can leave the parking lot at work and drive EV mode for about a half mile, to the interstate on ramp. Then drive home via interstate. The result is 5 min. consumption bars of
    50/45/60 MPG for 15 minutes. . If I don't use Ev the bars are 25/50/70 MPG. The end result actually is still in favor of EV, but you can see how it's use impacts second and third segment MPG.

    And 1/2 mile of EV can ruin 2 miles of stealth and glide.

    That being said, the Gee-Whiz factor is very high and I think I've learned to use it at the right times. Possibly I've seen 1-2 MPG gains since I've learned when to use it. It allows me reposition my car in the parking lot at work, without starting up, and I can reposition my car in/out of the garage for washing etc., without starting up. I can also force a stealth or glide with the EV switch under proper conditions that ordinarily would not have been allowed. One such example is during rush hour, and being stopped just prior to an uphill crest, that I know will be followed by a long downhill glide/regen. I can use EV switch to force a stealth that would have otherwise been impossible over that crest, with no cost on the downhill side. I think I just saved a little gas.

    I think I can midigate the downside of EV switch use by limiting the battery SOC that I EV down to .

    Worth the time and effort in my book..
     
  7. MikeSF

    MikeSF Member

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    <div class='quotetop'>QUOTE(TonyPSchaefer @ Nov 12 2007, 06:06 PM) [snapback]538659[/snapback]</div>
    Curious scenario here, maybe somewhat unique.

    I live on a hill, it's residential streets to the bottom of the hill to the freeway for work, however the ICE flips on and I get at best 20-25 mpg as it warms the car up on what ordinarily would be "free miles". Is the lack of a warm engine on a freeway going to negate any "free miles" I get with an EV flip for the downhill cruise?
     
  8. qbee42

    qbee42 My other car is a boat

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    <div class='quotetop'>QUOTE(MikeSF @ Nov 15 2007, 12:43 AM) [snapback]539839[/snapback]</div>
    Either way you are going to have to warm up the engine, and it appears that modest speeds are best for this. I suspect you are not gaining much if anything by using EV mode down the hill, unless you are doing a lot of sitting at lights.

    Tom
     
  9. mparrish

    mparrish New Member

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    <div class='quotetop'>QUOTE(MikeSF @ Nov 15 2007, 12:43 AM) [snapback]539839[/snapback]</div>
    The short answer to this thread's question is the following:

    (1) If you do not "hypermile", the EV switch will not give you much of a boost.
    (2) If you do "hypermile", the EV switch will give you a 10-15% mpg boost (over a typical 10-15 mile city trip).

    Your situation is similar to mine. I also live at the top of a hill, and before the EV switched endured low iMPG during warmup as I made my way down the hill. With the EV switch, I'm able to kill the engine as I go down the hill. My mileage got a 10-15% permanent boost on my commute to work.

    The EV switch is sometimes jokingly referred to as an "engine veto" switch. That's a more appropriate name, in that activating the switch only kills the engine. The switch allows you to begin a P&G cycle in stage 2 & 3a, effectively allowing you to warmup up the car at times (uphill, pulsing) when you would have had the engine on anyway and to turn it off at times (downhill, gliding) when you'd prefer not to have it on.

    Yes, you have to warmup to 180F+ anyway. And yes, using the EV switch to P&G right out of the gate after stage 1 does delay that warmup until you are farther down the road.

    But the costs of doing that are more than outweighed by the benefits of P&Ging right out of the gate after stage 1 warmup. Ask anyone who hypermiles with the EV switch and they will till you. My city commute in the summer went from ~70mpg to ~80mpg overnight, and there it stayed.

    If you say "no thanks" to hypermiling and are only interested for the potential MPG boost, then you can probably not bother.

    Edit: I should point out something very, very, VERY important. I use my EV switch ALL THE TIME during stage 2 & 3a warmup. It helps my mpg significantly. HOWEVER, I never, never, NEVER drive in electric only. You won't see yellow arrows on my screen, only a blank screen or green arrows. Yellow arrows is bad for mpg. But the switch is great provided you just use it to kill the engine.
     
  10. ServoScanMan

    ServoScanMan Member

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    <div class='quotetop'>QUOTE(stomsf @ Nov 12 2007, 06:04 PM) [snapback]538619[/snapback]</div>
    I'm not sure what your defintion of 'marked' is. My fuel economy has improved with the EV mode switch.
     
  11. omgitsroy326

    omgitsroy326 New Member

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    <div class='quotetop'>QUOTE(ServoScanMan @ Nov 17 2007, 05:42 PM) [snapback]541034[/snapback]</div>

    if my commute is two miles local .. then can i just use my ev switch the entire way granted i stay under say 35 mph and i have enough battery bars?
     
  12. statultra

    statultra uber-Senior Member

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    i use it to get from my driveway to the main road, ( its about a half mile ) then the main road has speed limit of 45 so i just disengage it.

    I do this to avoid warmup cycle sitting still, instead i find that avoiding the warmup cycle sitting still is more efficent, usually when i drive home i keep the cruise on so my battery goes up to the top, so the next morning i can use EV till i get to main road
     
  13. 9G-man

    9G-man Senior Member

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    <div class='quotetop'>QUOTE(omgitsroy326 @ Nov 17 2007, 10:57 PM) [snapback]541072[/snapback]</div>
    Depends on the topography of your commute. Any uphills? that will wipe your SOC quick...1/8-1/4 mile and you'll be left with a running ICE>
    And even if you do pull it off, then you reach your destination with low SOC and must run ICE on the way back, which may not return SOC to a high level, thus you won't do it again the next day.
    Good candidate for PHEV.
     
  14. lowredranger

    lowredranger New Member

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    So do you use your EV switch at highway speeds when pulsing and gliding to turn off the engine when you get to 75mph and turn it back on at 65mph to gain back up to speed?
     
  15. qbee42

    qbee42 My other car is a boat

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    No, it won't do that. The EV switch will ask the control system to run in electric mode if possible. Electric mode is not possible at speeds above the low 40s. Mostly the EV switch is good for moving a short distance in a parking lot, or reducing the amount of warm up the engine does.

    Tom
     
  16. Navigator

    Navigator New Member

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    I notice that on my commute, my worst mileage is almost always when first accelerating from a stoplight. Using the pedal alone, I cannot quite keep the car in EV mode without obstructing traffic, even though I almost always have green bars. So, what about using the EV switch to get off the line and then just let the mode switch back to normal at 34 MPH?
     
  17. JimboK

    JimboK One owner, low mileage

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    This is relevant to this thread. I hadn't written it when this thread first appeared, but since this one's been resurrected ....

    It might seem counterintuitive, but that's almost the exact opposite of how the EV switch should best be used. Bottom line: using EV for propulsion, whether via the switch or the pedal, generally will hurt fuel economy. Re-read this thread, read my writeup and the links within it, and do a good search on the other EV threads to fully understand why.
     
  18. Navigator

    Navigator New Member

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    This does seem counterintuitive! Even when I use the pedal to accelerate in EV only mode as much as possible, I still wind up with green bars. I think this is because I am not attempting to cruise in EV only mode all the time. There are enough stoplights to allow me to keep the battery charged up to the green bars. In view of this, it is hard to understand why using a bit of EV only mode for a few seconds just to get off the line wouldn't be beneficial.
     
  19. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I won't lie and tell you that I always do the right thing or that I never use the EV button "incorrectly."

    Oh sure, I have accelerated using the button. Sometimes I see little or no real impacts. Other times, I manage to drop my SoC a couple bars and then have to listen to my ICE rev up and recharge the batteries.

    So let me put this into another perspective: Should I drink this soft drink?
    - It's got a lot of empty calories so a lot of people would say no.
    - I like the taste so I might say yes.
    - All those calories might go to my waste so I probably shouldn't.
    - But I'm planning on going to the gym tonight so I could burn them off.
    and the back-n-forth could go on all night.

    In the end, if you have the button, use it to your heart's content. knock yourself out. We should not be telling you what you can and can not do. However, some of us have a few years worth of experience to tell you what happened when we used it in situations that might or might not be just like yours.
     
  20. Navigator

    Navigator New Member

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    Right, which is why I am asking you guys. Thing is, most of the posts I see regarding the EV button seem to be by people asking if they can cruise all over town in EV only mode. I haven't seen much about the impact of using the button only for, say, an occasional 5-second moderate acceleration.