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How To Drive Efficiently?

Discussion in 'Newbie Forum' started by Debra45, Feb 1, 2015.

  1. Debra45

    Debra45 Junior Member

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    Just purchased a used 2013 Prius Five. I'm confused about accelerating and coasting for best MPG and would appreciate tips for how to drive efficiently.

    Also, do you find that the instant read out for MPGs are accurate? Thanks!
     
  2. Easy Rider 2

    Easy Rider 2 Senior Member

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    Drive slowly.
    Accelerate slowly.
    Coast whenever possible.
    Actually come to a complete stop only when absolutely necessary (anticipate traffic and signals).
    Keep an eye on your tire pressure and keep it 2 to 4 pounds higher than the "recommendation".

    None of the displayed MPG figures are really accurate. Most owners find them 2-5 MPG on the high side.
    The instant readout is "accurate" only for comparison purposes; when it gives a higher number, you are doing better.

    Welcome to the forum.
    Your questions have been the subject of literally hundreds if not thousands of previous messages posted here.
    Please look for and read some of them.
     
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  3. vskid3

    vskid3 Active Member

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    This video is a good place to start.

     
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  4. CR94

    CR94 Senior Member

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    Right.

    In particular, coast as much as practical with the HSI display bar "disappeared" into the boundary between regeneration and "ECO." That will require depressing the accelerator just slightly. However, if you need to slow down more abruptly, braking lightly (keeping the HSI bar inside the left end of the display) is better than coasting without braking, followed by hard braking.

    The low-resolution instant MPG graph is too vague to be worth much, in my opinion. I think the consensus is that your actual average MPG is roughly 6% less than the car's average MPG display shows.
     
    #4 CR94, Feb 1, 2015
    Last edited: Feb 1, 2015
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  5. hill

    hill High Fiber Member

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    Welcome!
    Like everything we do - practice makes it better. I think of it like driving as if your brakes went out. That always makes you more careful. You WILL get better at mpg increasing over time.
    .
     
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  6. bisco

    bisco cookie crumbler

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    congrats and welcome!(y)
     
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  7. GregP507

    GregP507 Senior Member

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    ...and learn to ignore all the road-rage that this type of driving seems to produce.
     
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  8. Ashlem

    Ashlem Senior Member

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    To add to what others have posted, and was mentioned in the video, use common sense as well.

    Don't glide to a stop sign/light if there are other cars behind you. It'll only make them angry at you, especially during rush hour. Even if you have to go fast to stay with the flow of traffic, be content that you're still getting better mpg than every non-plug in vehicle there, or someone else driving a prius and knows how to "hyper-mile".

    When using the "regen brakes", what is actually happening is the electric motor is working in reverse, converting your momentum into electricity to refill the battery with. It's not a perfect conversion and not the most efficient way to get power. But at least you're able to do that with the prius and get some energy back, whereas in a regular car it just loses that momentum as heat on the brake pads.

    The actual brakes don't kick in unless you're going under 7 mph, or you full press it down (the blue bar is completely filled). The less you have to use them, the longer the brakes last. There are people who have gone 150-200k miles in their prius and are still using their original brake pads because of this.

    Give yourself time to learn how to utilize these techniques. It took me months to finally master the "press the accelerator gently so there's no green or blue on the HSI indicator bar", and I can only use it when there aren't cars behind me. But it's really nice to be able to coast and watch the mpg meter go up.
     
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  9. Mendel Leisk

    Mendel Leisk Senior Member

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    I wouldn't get too intimidated by other drivers. You don't have to push back either. Just keep doing what you're doing, coasting when it's pointless not too. Keep a good space in front is good for multiple reasons: you can eat it when the cars ahead, and it gives aggressive tailgaters an out.

    The more drivers cool it, the more the idiots stand out.
     
  10. GregP507

    GregP507 Senior Member

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  11. Easy Rider 2

    Easy Rider 2 Senior Member

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    So are you saying that we should somehow cater to those idiots who charge up to the end of a line of stopped cars and then slam on their brakes ??
    I don't think so.

    You should not be gliding when the cars in front of you are moving but if they are all stopped, anybody who doesn't like it can go pound sand.
     
  12. GregP507

    GregP507 Senior Member

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    Conflict resolution 101.
     
  13. Radiohound

    Radiohound Junior Member

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    I just bought a 2008 Prius with 42k miles on it. What a great car! Since I purchased it about 3 weeks ago, I have been utilizing glide to stop light tips, etc. In fact, I have long used many of these techniques to get 20 mpg in my 2001 4runner :) . They just work a whole lot better in the Prius! I have 42/40 psi cold (might have been higher on the 77 degree day (at least for the second part of the trip home).

    I recently read about some hypermiling tips. So on a leisurely trip from Gilroy to Oakland (pretty flat freeway), I tried to put what I learned to use. While normal gas saving techniques can be used by just about anyone (comfortably), some hypermiling techniques aren't for the faint of heart. I heard about the "sweet spot" where the current MPG can hover around 70 to 80 (70 to 99.9 really) mpg. This seems to occur around 50 to 60 mph and 1200 rpm or so on the Prius gen2. To drive this speed on a freeway rated for 65 mph can disrupt the flow of traffic. I think my wife would be giving me an ear full every mile 100 mile round trip, had she been in the car. But there were semi's doing this targeted speed, so I figured I could just travel (at a safe distance) behind them without irritating motorist any more than they already were. By letting up on the accelerator, and slowly bringing it up to travel at this speed, then feathering it very lightly to try to keep the current mpg to this hyper range. Sometimes I would find myself drop off behind the semi, and I would have to speed up, and then glide in and try again. Using this technique, and hitting a little stop and go traffic near Oakland, I was able to average 77.5 mpg during 119 miles (on the display).

    If I can do this on my first day trying .... a lot is possible with the Prius!

    [​IMG]
     
    #13 Radiohound, Mar 7, 2015
    Last edited: Mar 7, 2015
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  14. tanglefoot

    tanglefoot Whee!

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    Another technique is to accelerate fairly briskly (not "jackrabbit", but with a little bit of oompf) to just above the target speed and then coast or pulse/glide. The argument here is that the instantaneous MPG is low whenever the car is accelerating, so getting up to speed fairly quickly reduces the time duration at low instantaneous MPG and enables longer durations at higher instantaneous MPG, for a higher overall average. Choose the target speed wisely though--one that can be sustained for a while. Experiment with different acceleration rates to see which works best for you and which you prefer.

    Being aware of conditions up ahead (and all around) is a great technique for fuel economy (and safety). This also relates to the "Driving without brakes" fuel economy technique mentioned above. Excessive brake use, even with the Prius, wastes fuel. It's most efficient to anticipate stops and slow-downs and get off the power early to maximize coasting and reduce brake/regen use.

    The climate control settings make a significant difference with Prius fuel economy. In cold conditions, the Prius runs the gasoline engine more just to produce heat for the cabin heater (especially hurtful to MPG at a stop). The A/C creates an electrical drain on the system. I find it's most efficient not to use the climate control system in "auto" mode and instead, use it manually and miserly. In the cold, I usually try to drive the first few minutes before turning on the heat (when possible). In warm conditions, A/C off and windows down is usually most efficient and low speeds--windows up and a little A/C is most efficient at higher speeds (above about 40 mph).

    "Driving with load" is another effective technique. Pretend the car is a roller coaster: allow some speed to bleed off at the apex of hills and regain the speed on the downhill side (within reason). This is more efficient than maintaining a constant speed over hills (better than cruise control). Try to avoid accelerating on a climb.

    Practice finding and holding the spot in the go-pedal travel where energy flow is zero (or close). Use the energy flow screen as a training aid. It's just slightly down from the top. This is where you want to hold the pedal for the "glide" stretches. Letting the pedal up all the way activates some regen braking and bleeds off momentum (use this when needing to slow down). Too much pedal pressure draws electric-drive current (useful in some cases) and/or causes the gasoline engine to start/consume more fuel.

    Use electric drive, ("glide" or "stealth") strategically. Overuse can reduce fuel economy, but when used in low-load, limited duration conditions (parking lots, flat residential streets, traffic jams), it adds periods of infinite fuel economy into the average and really boosts the numbers. Stealth works best in warm temperatures with limited climate control demand.

    Work with the 42 mph speed threshold (unless this has changed after the 2nd gen). Above this speed, the gasoline engine must spin. Below this speed, the gasoline engine can stop. Glide (infinite instantaneous MPG) works best at 41 mph and below. Above 42 mph, fuel-free travel is still possible (warp-stealth), but more difficult and more energy-costly. When the desired speed is near the threshold, try to stay below it.

    On the highway, remember that wind resistance increases dramatically (power of 2) with speed. Cruising at 65 mph or below results in much less wind resistance than 75 mph and above.

    Good luck! It's a lot of fun, there's much to learn and try, and it can go completely nuts, but I enjoy a moderate level of hypermiling that isn't too obtrusive to other drivers.
     
    #14 tanglefoot, Mar 7, 2015
    Last edited: Mar 7, 2015
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