Guess what I found about the Prius !

Discussion in 'Gen 3 Prius Fuel Economy' started by Chris2128, Apr 13, 2011.

  1. pakitt

    pakitt Senior Member

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    Re: Guess what I found about he Prius !

    The Prius has a drive-by-wire gas pedal - there is no mechanical connection whatsoever between the pedal and the ECU/ICE. Hence when CC is on, the gas pedal can go back to its rest position.
     
  2. adamace1

    adamace1 Senior Member

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    Re: Guess what I found about he Prius !

    You can get the same mpg in eco or normal. A few say they get better mpg in power mode, but i do best in eco, then normal, and power uses the most gas.
     
  3. ItsNotAboutTheMoney

    ItsNotAboutTheMoney EditProfOptInfoCustomUser Title

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    Re: Guess what I found about he Prius !

    Normal = Not in any of the special modes (not ECO, not PWR, not EV)

    (Of course PWR mode makes the car behave "normally", with response like a regular ICEV. When tested for EPA purposes it's in "Normal", without any special mode on).
     
  4. Chris2128

    Chris2128 New Member

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    I'd like to agree with Mendel leisk, that the pedal comes back to orig position when we activate cruise control because it's drive by wire. But, IMO many cars I drove with drive by wire seemed to suck the pedal down when you set cruise. Haven't many of y'all felt that?
    Ok heres another funny feel. My car has the radar cruise so when it slows down or applies brakes, the brake pedal doesn't get sucked down either. It's at rest position and nothing happens to it at all. I guess we can call it "break by wire" :d but in my 2002 Infiniti q45 the laser cruise pulled the break pedal and you could feel the break pedal "disappear" if u know what I mean :)
     
  5. kgall

    kgall Active Member

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    Re: Guess what I found about he Prius !

    Yep, I've noticed huge differences between headwind and tailwind and sidewind along I-40 just east of you in Ark.
    About a year ago, someone posted a chart showing how wind would affect mileage based on a computer simulation. It showed that even crosswinds can significantly lower MPG, and you have to get pretty close to a real tailwind to before it benefits you.
    Anyone remember what thread that chart was in?
     
  6. Caug1

    Caug1 Member

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    Re: Guess what I found about he Prius !


    I am new here.
    What is SHM?
    THAnks,
    c
     
  7. dustoff003

    dustoff003 Blizzard Brigade #003

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    Super Highway Mode, beyond that I don't know much. It is more of a Gen. 2 thing, some kinda sweet spot for highway driving.


    Posted from my iPhone via the Tapatalk app.
     
  8. Caug1

    Caug1 Member

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    Re: Guess what I found about he Prius !

    I see,
    Thanks.
    c
     
  9. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    Re: Guess what I found about he Prius !

    Look at post #37 of this very thread. :D
     
  10. walter Lee

    walter Lee Hypermiling Padawan

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    Re: Guess what I found about he Prius !

    On long super highway trips (>100 miles in one direction over 50 mph) the cruise control does a better job at being more fuel efficient than if I manually control the throttle. The CC tends to adjust more quickly and in smaller increments than I can do manually. The ECO mode delay the throttle to enforce gentler accelerations and is useful in urban driving environments. In hilly terrain or on the superhighway or when quick variable acceleration control is necessary ECO mode may make it more difficult to manually obtain the best Fuel efficiency.
     
  11. fess-it

    fess-it Junior Member

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    Re: Guess what I found about he Prius !

    I found that tire pressure (big effect) and alignment (jury is still out) have a significant effect mileage. Don't assume the dealer inflates the tires properly. Check it yourself by bringing your pressure gauge. I did, and I found that the dealer didn't adjusts the pressure at all! Moreover, the front tires should be 35 psi and the back tire should be 33 according to what's on the door. I asked my dealer to do that and they said "Yea, I can do that!" Clearly it wasn't something they normally do. Once I got that straight my mileage went from 52 to about 56 mpg. I commute 60 miles round trip with stops on the way.

    Finally, if you get your tires aligned with a non-dealer, make sure it is to the proper specification. I had a debate with my non-dealer mechanic about the correct specification.
     
  12. Tideland Prius

    Tideland Prius Moderator of the North
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    @fess-it Feel free to bump it to 38/36 if you're ok with the slightly bumpier ride and the mpg will rise again.
     
  13. Old Bald Guy

    Old Bald Guy Old Bald Guy

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    Toook a trip to California from Dallas, TX in April. From west Texas into west New Mexico, we were running the cruise at 80 MPH and above. (80 is the speed limit on much of I-10 in west Texas.) When we stopped for the night and checked the weather, we learned that we had been fighting a 45 MPH headwind with gusts to 60. Our mileage into the wind was about 35 MPG.

    Coming back a week later, same road going east this time, just a little tailwind, and we logged about 55 MPG with the cruise on 80 MPH or above. I run ECO mode probably 99 % of the time.
     
  14. That_Prius_Car

    That_Prius_Car Austin Kinser

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    I think ECO mode is mainly for city driving and power is for interstate driving...? Right? That's confusing.
     
  15. pakitt

    pakitt Senior Member

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    The modes are not intended for any specific type of road, but enable to improve fuel economy by allowing more/less control of the request of power from the drivetrain via the gas pedal. This is why ECO mode in the city is better suited since you are stopping and accelerating way more often than on the highway. That said, once more, this is what the modes do:

    • ECO Mode: the gas pedal response is "toned down" offering the finest control possible on the Prius Gen 3; the A/C-heater functions are optimised for fuel consumption: in winter, this is achieved by keeping the ICE on less often, forcing the fan speed to be lowered to reduce the "wind-chill" effect, since cooler air is blown in the cabin; in summer, this is achieved by using aggressively recirculation, while throttling down the A/C compressor; these changes in the way the A/C-heater work, are to be seen, based on my experience, only if AUTO mode is on
    • Normal mode: well - normal, this mode is active when neither the ECO mode nor the PWR mode lights in the instrument cluster are on; no changes in A/C-heater functioning
    • PWR Mode: the gas pedal is most reactive; the ICE tends to stay on when releasing the gas pedal to improve response of the drivetrain when depressing the gas pedal again; no changes in A/C-heater functioning
    • EV-only Mode: the drivetrain is forced to use the MG2 only until the SoC allows it; ECO mode/normal mode/PWR mode will still affect gas pedal response, i.e. if PWR mode is active when EV mode is engaged, the car will accelerate more promptly than if ECO mode were on; obviously this will discharge the battery faster since more powerful accelerations will require more current; EV-Mode, due to its limited range of action (2km/1.25mi at most, on a fully charged battery) is not really to be considered a "driving mode" as the 3 above mentioned ones

    Additional details here.

    Now a list of things that are good to know about the modes:
    1. the same amount of power is available in all 3 modes, e.g. kick-down will provide the same performance in all 3 modes (there is a video showing exactly this here) - there is also a nice chart in the same thread showing the gas pedal throttle response in all 3 modes; at constant speed the modes do not make any difference in the performance of the car (expect the A/C-heater changes in ECO mode, that might improve FE since less energy is required to keep the cabin at a set temperature)
    2. the fuel consumption might not be affected by using the 3 modes - fuel efficiency is greatly dependent on how one accelerates, traffic, type of roads, etc.; there are users on PC that claim very good FE in PWR mode, others that cannot get a good FE at all in PWR mode
    3. there are no measurements or objective tests/results showing that keeping always the same mode has any effect on the lifetime of the car as whole or on the battery/hybrid drivetrain
    4. there are no measurements or objective tests/results showing that the 3 modes have any effect on the way the cruise control responds to changes in road inclines
    5. there are no measurements or objective tests/results showing that changing the modes will change: the steering wheel response; the maximum voltage allowed on MG2 in ECO mode (e.g. 500V instead of 650V; there is such a claim for the Lexus CT200h, that shares the same drivetrain as the Prius Gen 3, between ECO/normal mode and Sport (PWR) mode); the ICE management (e.g. changes in the valve opening times, etc.) or the way the ECU provides current (i.e. more in PWR/less in ECO) for the same acceleration/power request (same HSI bar length) to MG2

    The modes are, except for the A/C-heater performance, in essence "psychological" ways to help the driver get the best FE, by affecting the way he/she accelerates the car to a certain speed.

    Looking at the modes from this perspective, one could therefore say that:

    • ECO mode is better suited for stop&go city traffic, where frequent stops and accelerations could lower FE if the driver accelerates aggressively (due to personal style, or traffic flow) several times in a row in short trips
    • Normal mode is best suited for suburban driving with less traffic and stop&go situations, as well as for highway; good to excellent FE might be achieved in city traffic if a light foot is used, traffic flow allows for slower accelerations and temperatures do not force the ICE to be on longer than necessary to keep the battery charged;
    • PWR mode is perfect to get with less "psychological" effort (i.e. no need to "stomp" on the gas pedal) more responsiveness from the drive train on winding-mountain roads (e.g. more fun drive), merging on an highway quickly without feeling that you need to kick down to get to speed, to get quicker overall response by keeping the ICE on more often

    In winter ECO mode does a better job in increasing the FE by keeping the ICE more often off in city traffic by reducing wind-chill while blowing less warm air (on average) and using recirculation more aggressively (as well as in summer...).
    My personal experience shows that I cannot get good FE in city traffic with PWR mode as I cannot fine tune the gas pedal as I would like.
    I use ECO mode on the highway at constant speed to reduce fuel consumption benefitting from the A/C-heater "down-throttling".

    If you drive aggressively no mode will help, your FE will not be good. If you drive sensibly usage of PWR mode may not affect visibly your FE performance, or even improve FE on trips with long sections where no sharp accelerations are required (e.g. like at traffic lights, or when merging onto fast traffic with short speed-up lanes).

    I think I will add the contents of this post to the Prius Wiki since this topic comes out ever so often....
     
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  16. Dark_matter_doesn't

    Dark_matter_doesn't Prius Tinkerer

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    I've noticed that in ECO mode, the battery SOC stays consistently higher than in Normal mode, as if that's a priority. I'm not sure if it's because of more ICE operation (which is counterintuitive for this mode) or more aggressive regen from braking.
     
  17. pakitt

    pakitt Senior Member

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    It is likely because you tend to accelerate less aggressively and therefore require the need of the battery much less than, say, Normal mode.

    I personally noted the battery tends to stay more charged in PWR mode, and in ECO mode if I accelerate always starting with the electric motor only until 20km/h and after that by keeping the HSI bar shy to the right of the middle line (this is also how I get the best FE so far on my city commute). I can do this type of accelerations since traffic allows for it.
     
  18. motoleon

    motoleon Junior Member

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    I have data, vía OBD, that shows that at constant speed, no hill, in PWR mode the ICE goes at HIGHER RPM than in ECO mode (at 90 kms/h 1600 rpm vs 2400 rpm). It is very interesting thing, and we have to think about this.:rolleyes:

    Salu2.
     
  19. pakitt

    pakitt Senior Member

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    It is my theory that there is not just a mapping of the gas accelerator going on. But I am always reading that it is not. It is *just* a mapping of the accelerator.

    Since you have data via OBD, yes - please do investigate further.
    For one thing, the ICE does not turn off as it does in ECO mode when releasing the gas pedal. It stays on waiting for the next acceleration - and turning off the ICE would mean having a delayed response.

    The fact that at constant speed the ICE runs at higher RPM, could lead to think that in PWR mode the ECU tries to keep the battery always well charged, to give that extra boost from MG2 when accelerating.

    We need to check, check, check....
     
  20. arnettjs

    arnettjs My gas guzzler pulls my boat!

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    Re: Guess what I found about he Prius !

    lmao!
     
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