149 MPG on a 52 Mile Commute: An Analysis

Discussion in 'Prime Fuel Economy & EV Range' started by TJX, Nov 20, 2017.

  1. TJX

    TJX New Member

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    Hi everyone,

    Had my Prime for just over 3 weeks now, and I've been playing around with a few different routes and driving styles to optimize my MPG. I think I've landed on a pretty decent approach. I'm sharing my driving strategy, complete with online tools and a few images to illustrate my route in order to share what worked for me, but also to solicit whatever useful tips other may have to optimize my fuel efficiency. The following is some data I took on today's commute:

    [​IMG]
    Commute Eval2.jpg
    [​IMG]

    First a few preliminaries:
    • Round trip distance is 51.6 miles, mostly rush-hour highway driving but stop-and-go city driving as well.
    • Temperature ranged between 34 and 40 degrees on the morning commute to work according to the console display; 45 degrees on the evening commute back home.
    • Climate control set to 60 degrees in the morning, off in the evening.
    • Heated seats both ways
    • Elevation difference between work and home is 185 feet: descending in the morning, ascending in the evening.
    • Battery fully charged in the morning.
    The following graph shows the change in elevation of my round trip commute. I've also numbered the different stages of my route based on how the route or my driving style changed. Basically, my approach is to use EV Mode when driving in stop-and-go traffic and climbing steep hills, and switch to HV Mode when driving at highway speeds on a relatively level plane. I find that the mode is irrelevant when descending steep hills because either way the ICE shuts off when coasting.

    Commute Strategy.jpg

    Green: EV Mode
    Red: Hybrid Mode
    Purple: Toggled back and forth

    Commute to Work
    1. EV. City Driving. Top speed 45 MPH
    2. HV. Highway driving. Cruise control set at 57 MPH (all highway driving at this speed)
    3. EV. Highway driving. EV Mode turned on for steep incline.
    4. HV. Highway
    5. EV. Highway. Hit traffic. Stop-and-go for nearly 5 miles. Top speed 20 MPH.
    6. EV. Parkway with 6 traffic lights on route. Top speed 50 MPH.
    7. EV. City Driving. Top speed 25 MPH

    Commute Home
    8. EV/HV. Toggled between modes for city and Parkway with traffic lights. EV to accelerate; HV to cruise.
    9. HV. Highway.
    10. EV. Highway.
    11. EV. City. EV battery nearly depleted upon arriving home - 0.1 miles left in electric range.

    Would appreciate any suggestions for improvements anyone may have. Thanks!
     
    #1 TJX, Nov 20, 2017
    Last edited: Nov 20, 2017
  2. idleuser

    idleuser Member

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    I drive the same way as you toggling between HV and EV mode. However, I only managed to achieve 102.8 MPG today traveling around 70MPH on the high way and between 40-45 on streets.

    Round trip for me today is around 62 miles.
     
  3. Tideland Prius

    Tideland Prius Moderator of the North
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    Question:

    For the first 16 miles, would EV Auto reduce the amount of button pressing? Basically just for segments 1-4. Kinda curious to see since EV Auto is supposedly to help gain the most efficiency and given that you're in HV mode while climbing, it's possible that in EV Auto, you may surpass the threshold (that we've yet to determine) to allow the engine to come on and effectively be in HV mode for segment 2 instead of climbing in EV mode.

    I think the return trip home is fine in terms of what you're doing.
     
  4. TJX

    TJX New Member

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    Not much you can do about the distance to work, and 103 MPG is awesome. I wonder, have you noticed your breaking habits? I noticed when I changed my breaking habits by letting off the gas earlier when coming to a stop, my gas mileage started improving measurably. And obviously reducing speed will help as well (not telling you anything you don't know), although if you're traveling a 65 MPH road, then I supposed you really can't go much slower than 70.

    What I love about owning this car is how dramatically my expectations have shifted in regards to good gas mileage. When I owned my Avalon, I was thrilled when I finished a trip at 32 MPG. Now I regard 130 MPG as a personal failure, LOL.
     
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  5. TJX

    TJX New Member

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    That's a great suggestion. I'll try EV Auto mode for a week or so, and see if that squeezes out a few extra MPGs.

    Thanks!
     
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Thanks for testing it out for us!

    We're still figuring out as a group what EV Auto does specifically and when to best employ it. Based on the limited amount of data we have, it appears Segment 1-4 would be the perfect use (and I guess 5-7 would be in EV mode anyway... even if you were in EV Auto assuming reasonably flat grade and no hard acceleration needed).
     
  7. ct89

    ct89 Active Member

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    If you're up for experimenting, it might also be interesting to know how the results would be if you just drove the car and never bothered switching modes.

    What is your net average mpg difference (or ultimately commute cost difference) between manually optimizing and just driving?
    From what you show above, you're using 0.3465 gal each day. That's 90 gal/year or about $270 for a yearly commute (at $3/gal).

    My guess (and we can start a poll) is that you'll see something closer to 125mpg with the just-drive-it mode which would translate to 0.4128 gal each day or about 107 gal/year. About $50 more.

    Since this forum likes to really examine details, we should evaluate the replacement cost of the EV mode button as you will be pressing it almost 3000 times a year to save the $50 and since it might wear out we should subtract some replacement cost from the net savings...:)

    All kidding aside, thanks for the detailed data...It is interesting.
     
  8. ct89

    ct89 Active Member

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    What you achieved is exactly what you would expect if you drive 25 miles on EV and the other 37 miles on HV @ 62mpg...
     
  9. idleuser

    idleuser Member

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    Yea I'm not complaining. I just wanted to give people another point of reference if they decide to drive it like a normal car. I am not patient enough to be hypermilling every mile :)
     
  10. Andyprius1

    Andyprius1 Senior Member

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    Looks perfect to me.

    Yes, I’m also trying ev auto now.
     
    #10 Andyprius1, Dec 2, 2017
    Last edited by a moderator: Dec 2, 2017
  11. TJX

    TJX New Member

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    Quick update re EV Auto. I've tried it for 3 days now instead of pure EV Mode with more or less the same parameters, and there has been no discernible difference. ICE engine didn't kick on at all in EV Auto mode.
     
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  12. Tideland Prius

    Tideland Prius Moderator of the North
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    So it basically saved you from button pressing? :D
     
  13. Andyprius1

    Andyprius1 Senior Member

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    I have done the same, it eventually uses my preciously saved EV charge and of course the engine comes on from time to time. I still like Eco in starting out and Ev/Eco upon return. Although, Auto, also seems good.
    Ahs confused. But it’s not world shattering. Millions of people starving and we keep occupied by discussing Prime. It’s weird!
     
  14. 4rpr15

    4rpr15 Senior Member

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    If I have a 19 mile round trip commute to work wouldn’t it be better for me to leave it in EV mode all the way through? Once EV is done doesn’t it automatically change over to HV mode?

    When it’s freezing cold I use the following: Remote A/C for 10 minutes prior to departure, seat heater, ECO mode and I leave it in Eco Mode to and from work.
     
  15. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    To me, this is ideal for you. For a 19 mile round trip, I'd go EV all the way. Even in the very cold, you're going to make it all the way in EV or get very close. The only thing better is to also charge at work, guaranteeing a 100% EV commute unless it's very, very cold in which the ICE will run anyway with no choice.

    Yes, when EV is used up, it automatically reverts to HV mode.
     
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  16. 4rpr15

    4rpr15 Senior Member

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    So realistically the only reason I would need to go back and forth on modes is on the weekends with highway driving.
     
  17. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    Do you mean switching manually? I run mine in EV until it runs out and switches to HV mode. If the trip distance is inside the EV range, wonderful. If it's not, no biggie, I still have to get there and back.

    Some play with saving EV battery for certain segments of a trip, etc. I've not done much of that in my trips due to the nature of the trips. You can experiment, but I don't think it's going to make a "massive' difference. The "way" you drive will probably make the most difference than any mode switching methods will.
     
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  18. inferno

    inferno Senior Member

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    Very interesting. I've been getting around 140 mpg in the winter and 210 mpg in the summer on my 50 mile commute. I use ev when possible, using the coach as my guide. I basically feel the Ev portion in hv mode and throttle a little above it in ev mode. If I go further I switch modes.

    Steep hills I use hv mode. Downhill I coast and shift to B which is extremely helpful in ev mode.
     
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  19. thoatvidiadem

    thoatvidiadem New Member

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    wwoww. this post is great
     
  20. TJX

    TJX New Member

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    Funny, I just checked back in to update much of what you just mentioned. I was playing around with different modes of driving, and found that two changes increased my mileage measurably:

    The first discovery I made was switching to HV mode when climbing steep hills (which you apparently had already figured out). Steep inclines do a number on electric mileage. I suppose gas isn't as inefficient for this.

    Second, I found that it's better to deplete my EV range entirely for the trip home so the last 4.5 miles of city driving is done with HV. This is counterintuitive, since city driving in electric is much more efficient than gas. But if you quickly accelerate, release the gas, and then lightly reapply your foot to maintain speed, then most HV driving can be done in electric. So it's almost like squeezing out a few additional electric miles even after burning through the EV portion of the battery.

    In any case, making these changes, I noticed that yesterday under the same driving conditions with roughly the same temperature (30 degrees drive to work, 40 degrees drive home), my gas mileage was 165. Today it was warmer - 40 degrees driving to work, 50 degrees driving home - and my mileage was 182. So I can totally see how you're getting just over 200 mpg in the summer. Hopefully I will see similar results in the summer months :)

    I'm still amazed by this car.
     
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