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What's the best strategy?

Discussion in 'Gen 2 Prius Fuel Economy' started by gnagel, May 16, 2006.

  1. gnagel

    gnagel New Member

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    I've had my Prius for about 5 weeks now. I'm pleased with the performance so far---first tank (55.2 mpg), second tank (55.7 mpg), third tank (55.1 mpg). I would really like to see if I can take the fuel economy to the next level.

    My strategy for maximizing the fuel economy so far is to use the electric motor (yellow arrows) whenever possible. I can sometimes drive for 3 or 4 miles on yellow arrows alone with a 99.9 mpg reading. Of course, my average mpg on the tank increase substantially during these stretches. Granted, this method reduces the battery's charge, but I am usually in a situation after that stretch that requires braking and accelerating---so the battery naturally gets recharged again soon enough anyway.

    I've been reading some threads recently about pulse and glide. Let's say I'm driving at 35 miles per hour on a road with little traffic. Am I better off maintaining this speed using all yellow arrows or am I better off pulsing up to 40 mph and then letting it glide (no arrows) until the speed diminishes to 30 mph and then pulsing it back up again? I tried the pulse and glide method this afternoon and it seems that I lose the speed rapidly.

    Any thoughts?
     
    #1 gnagel, May 16, 2006
  2. efusco

    efusco Moderator Emeritus
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    3-4 miles...on level terrain...with only yellow arrows? That seems a bit further than I've every gotten. If it's a long downhill then sure, but 4 miles is a long way.

    If the conditions you describe exist, that is you can sustain the yellow arrows only for the full distance then recharge at the end with regeneration then that is doubtless the best technique.

    For most of us mortal drivers we can only sustain speed on level terrain with battery only for about 1/2 mile at 35mph...and even that isn't easy. In those cases, if you're driving for high mileage and traffic is not an issue then pulse-glide may improve your mileage.

    In reality, what I do anyway, is set the cruise control on level terrain. I have no doubt in my mind that the HV ECU is as efficient as I am on level terrain and prefer to let it do it's job. On rolling terrain I think I do better than the car and tend to manipulate the drive to maximum benefit with pulseing uphill, gliding downhill and level, etc.
     
    #2 efusco, May 16, 2006
  3. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    THe north half of Illinois - like Indiana - has seen a couple of glasiers come through in the last couple hundren million years (if you believe in that stuff). Therefore, I can speak for long stretches of very flat and sometimes even slightly downhill sloping terrain. And considering that Orland Park is as far South in Chicagoland as I am North, if Gnagel is heading due South it wouldn't be long before he's in farmland with no curves and no stoplights for many miles. Man I wish my drive was like that. I'm so jealous.

    But even with that, I find it extremely difficult to maintain a stealth (pure battery, 99.9MPG) for stretches longer than what Evan describes above. But the real question I have has to do with your sanity: if you are driving those long, straight, uninterupted stretches what in the heck are you doing driving under 40 MPH? Open it up, baby and see what that Prius can do!!
     
    #3 TonyPSchaefer, May 16, 2006
  4. troe

    troe New Member

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    I have had my Prius for two weeks now. I live in Panama City, Florida, so it is relatively flat, but I routinely run on battery alone for three or four miles, the key is to get just above your speed with the engine, take your foot off the peddel for three or four seconds and then very lightly touch the accelerator to keep your speed range. any sudden movement of your foot will immediately cause the engine to come back on. You can give up a little speed going up a small hill and keep the motor on battery. This all only works below 42 MPH, but that is a lot of my driving, and I have been averaging over 60 MPG with this tactic, Try it and see if it works for you. :D

    <div class='quotetop'>QUOTE(efusco @ May 16 2006, 01:11 PM) [snapback]256367[/snapback]</div>

    I forgot to add, I get a lot better milage with the bars that I can looking at the arrows.

    <div class='quotetop'>QUOTE(TonyPSchaefer @ May 16 2006, 01:32 PM) [snapback]256376[/snapback]</div>
     
    #4 troe, May 18, 2006
  5. SomervillePrius

    SomervillePrius New Member

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    If you see yellow arrows you are using energy stored in your battery. The energy has to get in there somehow and on level ground that means you have to use your gas engine to store it. Using your gas engine to recharge your batteries and then using your batteries to drive the wheels is inefficient. It's better to have the engine drive the wheels directly.

    So the best to go for is "no arrows" and then another "magic" state where the ICE is driving the wheels with no recharge to battery happening. This becomes what's called pulse and glide and is what the marathoners used to get really high numbers. This will means accelerating to 40mph and then coasting down to say 30mph.

    In real traffic this will annoy the hell out of people and will lead to dangerous driving at times. In real life I'm sure running on battery at times is not bad as you will recharge your batteries when you have to break or actually accelerate with the ICE.

    So for 2-3 miles you can get a killer MPG using the EV mode only, but your whole tank will be lower then a person that consistantly used pulse and glide for the whole tank
     
    #5 SomervillePrius, May 18, 2006
  6. j24816

    j24816 New Member

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    <div class='quotetop'>QUOTE(SomervillePrius @ May 18 2006, 08:29 AM) [snapback]257498[/snapback]</div>
    A good point. Safety and considerate driving should take precedence over MPG.
     
    #6 j24816, May 18, 2006
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