1. Offline

    iamnotasuperhero New Member

    Member Since:
    Apr 10, 2012
    Posts:
    7
    Likes Received:
    0
    Location:
    PA
    Your Vehicle Year:
    2012 Prius
    Model:
    Two
    So I just got a 2012 Prius Two, upgrading from a 12 year old Camry, and I'm trying to figure out the best way to do things.

    I've been poking around looking at some of the tricks to maximize MPG's, especially keeping the car in stealth mode 25 < x < 45 MPH (or so, basically looking at the bar and looking for EV mode to pop up).

    I commute on a lot of back roads to work, a 40 minute or so drive, with some hills, stop signs and stop-and-go traffic.

    My question is: once the engine is warmed up, wouldn't it be beneficial to switch the car to EV mode only for the initial acceleration at stoplights or stop signs?

    I'm new at this, but I would imagine that if you can put up with the lower level of acceleration (it does kick you out of EV mode sometimes due to that), you should be able to really save a lot on that initial "kick" of gas to get the car from 0 MPH to 25 MPH. I'm guessing, with my high-school-level knowledge of physics that the amount of power to push your hybrid from 0-25 would well exceed the amount of power required to charge the battery along with gas-powering the car for that distance.

    When the car is "warming up", it kicks you out at 10 MPH if it allows you to do it at all, so all this is moot unless you get up to that magical 5 minute threshold, I think.
  2. Offline
    • Moderator

    Paradox Prius Enthusiast / Moderator

    Member Since:
    Sep 22, 2005
    Posts:
    7,475
    Likes Received:
    2,405
    Location:
    N.Y.
    Your Vehicle Year:
    2014 Prius v wagon
    Model:
    Five
    The problem is you get hardly any acceleration using EV mode on a Prius liftback. The Prius Plug-in is a different story, but on a liftback in order to accelerate at a decent rate the engine will come on irregardless of being in EV mode. Basically, if you stay below the middle of the HSI bar while in HV mode it's the same as being in EV mode in that the engine won't come on until more than halfway into the bar.
    1 people like this.
  3. Offline

    ny_rob Senior Member

    Member Since:
    Feb 28, 2012
    Posts:
    1,627
    Likes Received:
    559
    Location:
    L.I.- NY
    Your Vehicle Year:
    2014 Chevy Volt
    1 people like this.
  4. Offline

    iamnotasuperhero New Member

    Member Since:
    Apr 10, 2012
    Posts:
    7
    Likes Received:
    0
    Location:
    PA
    Your Vehicle Year:
    2012 Prius
    Model:
    Two
    Thanks for the feedback. I agree the acceleration is a problem with this (how I'd love to hack that!) but I was asking because I was noticing that in EV mode you can get a somewhat better acceleration in the 10-25 range that makes it a bit more manageable. Basically, if you get over the hump, you can still accelerate all-electric (rather than just the dark green tha switches to EV mode automatically) in EV mode - up to 25 MPH, however. It requires a light touch on the accelerator (as does everything on the Prius, it seems), but I'm guessing that it could be a real saver in MPGs.

    I emphasize I'm really new at this, but I find myself wishing that the thresholds were about 5 MPH higher for everything, i.e. EV mode switching at 30 MPH, EV mode at startup switching at 15 MPH, etc. All that could be simply for considerations of battery life, though: a bunch of times now I've run the battery to two bars.
  5. Offline

    iamnotasuperhero New Member

    Member Since:
    Apr 10, 2012
    Posts:
    7
    Likes Received:
    0
    Location:
    PA
    Your Vehicle Year:
    2012 Prius
    Model:
    Two
    Here's what I'll do, inspired by the Power Mode thread. I'll do a scientific test, using my commute with frequent stop signs/stop lights through mostly suburban areas as a control.

    Starting tomorrow, I'll lodge the MPG's based on the on-board calculations, both ways.

    Trial 1: Normal Mode driving, with EV acceleration trick at dead stops (this might include full stops at lights)

    Trial 2: Normal Mode driving, regular

    Trial 3: ECO mode driving with EV acceleration trick

    Trial 4: ECO mode driving, regular

    Trial 5: PWR mode driving with EV acceleration trick

    Trial 6: PWR mode driving, regular

    Personally, I'm pretty dubious about some of the claims in PWR mode in terms of my commute, but we'll see. On my regular commute home yesterday I did get > 60 MPG calculation with ECO and the EV trick.
  6. Offline

    ny_rob Senior Member

    Member Since:
    Feb 28, 2012
    Posts:
    1,627
    Likes Received:
    559
    Location:
    L.I.- NY
    Your Vehicle Year:
    2014 Chevy Volt
    When running your tests- be sure to compare on the same leg of the trip. Home to work is not = to work to home. Yes, the distance may be the same, but too many other factors make them dissimilar for fuel consumption comparisons. I usually see 3+ mpg difference between the two trips each day (home to work is more downhill driving).
  7. Offline

    iamnotasuperhero New Member

    Member Since:
    Apr 10, 2012
    Posts:
    7
    Likes Received:
    0
    Location:
    PA
    Your Vehicle Year:
    2012 Prius
    Model:
    Two
    Absolutely, that's what I will do! I'll log a To: and From: for each trip, and we'll find out the results.
  8. Online

    friendly_jacek Senior Member

    Member Since:
    Oct 3, 2010
    Posts:
    1,686
    Likes Received:
    319
    Location:
    southeast US
    Your Vehicle Year:
    2010 Prius
    Model:
    II
    My answer is no, as you are putting a lot of stress on the traction battery and getting worse MPG when the battery eventually gets replenished from ICE.

    You should use the gas engine as much as possible when energy demand is high (ie acceleration and high speed driving) and use electric juice judiciously only for low energy demands (gliding and low speed driving).
  9. Offline

    Sergio-PL Member

    Member Since:
    Jun 24, 2011
    Posts:
    158
    Likes Received:
    39
    Location:
    Poland
    Your Vehicle Year:
    2011 Prius
    Model:
    N/A
    I agree but on the other hand I read on the other threads that ICE is ineffective below 30kmh. Stressing the engine below that speed by starting hard from the stop will also stress other parts of the drivetrain, wheels, gears, tires and steering stuff.
    I would recommend smooth acceleration from stop by steady increasing accelerator pressure to reach HSI optimum zone when car reaches 30 kmh or about 18-20 mph.
    It would be also very smooth for passengers as ICE ignition is almost invisible at that speed.

    My trip from and to home is different even by 1.0l/100. It's about 20%.
  10. Offline

    Erikon Active Member

    Member Since:
    Dec 5, 2009
    Posts:
    819
    Likes Received:
    102
    Location:
    Rochester, NY
    Your Vehicle Year:
    2010 Prius
    Model:
    III
    Realize that the electricity largely comes from the ICE burning gas to charge the battery. When you drain it down to two bars it's going to make your MPGs far worse than they would be until the battery is charged back up! I used to do this when I first got my Prius, EV was so much fun! But try running the same route with the battery low and the battery high and see how your mileage is!
  11. Offline

    9G-man Active Member

    Member Since:
    Jul 2, 2005
    Posts:
    1,237
    Likes Received:
    146
    Location:
    Atlanta, GA
    Your Vehicle Year:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Starting off in EV mode is robbing your battery of valuable charge that would better be used once you are up to speed, to increase your mileage for miles and miles. A few feet of EV travel to get going from a full stop is Depleting the battery, and that will put the car in a very inefficient mode of operation, while it moves the car and recharges the battery.
    Get going and up to speed with the ICE and then keep yourself going with electric and momentum. Thats the way to do it.
  12. Offline

    fattymoocow New Member

    Member Since:
    Mar 29, 2012
    Posts:
    97
    Likes Received:
    7
    Location:
    Richmond, VA
    Your Vehicle Year:
    2012 Prius
    Model:
    Four
    Hahahahaha. Off topic, but I just wanted to let you know I laughed so hard at this comment and I'm sitting in my cube at work. :D
  13. Offline

    iamnotasuperhero New Member

    Member Since:
    Apr 10, 2012
    Posts:
    7
    Likes Received:
    0
    Location:
    PA
    Your Vehicle Year:
    2012 Prius
    Model:
    Two
    I'm just starting out my scientific test for this, but the preliminary results of "Normal Mode with EV trick at stoplights" seems to be a significant bump in gas mileage over just running it in "Normal mode"... but with the tradeoff of running down the battery, which would make sense. It's just one test thus far, but today I got >7 MPGs over normal mode. (hitting the EV trick five times on the 16 mile commute). I did hit "Low Battery" a couple of times, preventing me from going into EV mode those instances.

    In order to satisfy my levels of scientific curiosity, I'd have to do my commute at least four more times each to get a decent average, but if the numbers are indeed +7 MPGs I think that's awfully significant. Even if the average is +5 it's pretty eye-opening. But it hits up against questions about the battery - whether it's good to run it down to two bars routinely, is it possible (or desirable) to trickle-charge it at night, etc.

    I'm already eyeing "PWR mode, EV mode at stops" as an interesting combination. Presumably PWR mode would charge up the battery more, but you'd still get the benefits of the EV at dead stops.
  14. Online

    friendly_jacek Senior Member

    Member Since:
    Oct 3, 2010
    Posts:
    1,686
    Likes Received:
    319
    Location:
    southeast US
    Your Vehicle Year:
    2010 Prius
    Model:
    II
    If you gain MPG on display, but end up with low battery, the study is inconclusive. You should do more than one trip to compare. I would suggest a week of driving with EV on vs week with EV off.
  15. Online

    friendly_jacek Senior Member

    Member Since:
    Oct 3, 2010
    Posts:
    1,686
    Likes Received:
    319
    Location:
    southeast US
    Your Vehicle Year:
    2010 Prius
    Model:
    II
    I agree that below 30 km/h ICE is inefficient for steady speed driving as the energy demands are very low at that speed and most energy will be wasted just to turn the engine. This is why hybrid turns engine off in such speeds. But we are talking about accelerating when you can easily put the engine in the efficient powerband and later glide. This is exactly why the best results are made with the pulse and glide technique. The shortest engine use the better.

    As for the "stressing" the engine, ICU loves to be stressed, otherwise gets carboned up with babying. You cannot say the same about battery and electric motors.
  16. Offline

    iamnotasuperhero New Member

    Member Since:
    Apr 10, 2012
    Posts:
    7
    Likes Received:
    0
    Location:
    PA
    Your Vehicle Year:
    2012 Prius
    Model:
    Two
    You're right, from 0-10 the engine basically automatically uses EV mode as long as you keep it inside the green area and don't leadfoot it. It's in that 10-25 area where you can get extra EV when you use EV mode over the regular operation of the car, with (crucially) acceleration into the white area.

    I guess one debate seems to be: "why bother with that when you want to save your power for pulse and glide?" A fair point, but if the difference is 5+ MPGs, over the regular operation, I think that's an interesting tradeoff. I'll see as I go through a week's worth of tests.
  17. Offline

    9G-man Active Member

    Member Since:
    Jul 2, 2005
    Posts:
    1,237
    Likes Received:
    146
    Location:
    Atlanta, GA
    Your Vehicle Year:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    And what was your baseline MPG in "normal mode" , that you are now exceeding by 7 MPG?

    Is that a single, one-way travel improvement, or a complete tank average improvement.

    If you are doing anything to hit "low battery", the gains you achieved by doing that are lost in multiples by the inefficient battery-charging mode you forced the Prius into.
  18. Offline

    iamnotasuperhero New Member

    Member Since:
    Apr 10, 2012
    Posts:
    7
    Likes Received:
    0
    Location:
    PA
    Your Vehicle Year:
    2012 Prius
    Model:
    Two
    It's looking more and more like the MPG gains I'm getting are coming because I'm becoming more efficient at getting to that 45 mph sweet spot and doing EV/coasting.

    After 3 commutes:
    To Work: 50.8 MPG, 54.3 MPG, 58.8 MPG

    But I'll still go through the exercise of trying to compare the EV mode at stoplight thing anyway - so that we know!

    Last week I did the EV mode at stoplight trick and got something like 57.7. But I'm going to get more data points. Who knows, I might get it above 60! :)
  19. Offline

    Prius2012hotness New Member

    Member Since:
    Apr 22, 2012
    Posts:
    11
    Likes Received:
    1
    Location:
    Tampa, FL
    Your Vehicle Year:
    2012 Prius
    Model:
    Three
    Without the trick I was getting 40-42mpgs doing A LOT of sub 30mph stop and start .. add in the ev mode for acceleration and ive been floating in the mid 50s all week so far (5 trips so far). Im a believer, will update you if I see a performance change due to low battery though all the braking does a considerable job of charging the battery.
  20. Offline

    ProximalSuns Senior Member

    Member Since:
    Mar 24, 2012
    Posts:
    1,882
    Likes Received:
    14
    Location:
    PNW
    Your Vehicle Year:
    2012 Prius
    Model:
    Three
    I think so and I do exactly that. You can accelerate pretty good from a stop light and that 0-15 mph is a big gas consumer.

    Only caveat is that battery typically needs to be full and some other issues as often the car won't let you go into EV mode.

    But often enough to be fun giving the car a mini-me EV aspect.

Share This Page