3.7 l / 100 km (63.5 mpg) in hilly rural terrain

Discussion in 'Gen 3 Prius Fuel Economy' started by zebekias, Aug 24, 2014.

  1. zebekias

    zebekias Member

    Joined:
    Aug 12, 2014
    100
    34
    0
    Location:
    Greece
    Vehicle:
    2010 Prius
    Model:
    N/A
    I'm happy to report that today I did the following route https://goo.gl/maps/cPsKA in both directions, going east at around 2:30pm and coming back around 4:30pm, ambient was about 33 C, no substantial wind. I started with half tank of gas and 3.9 l / 100km avg consumption displayed by the computer, and ended with 3.8 l / 100km. Silly me I didn't pay attention to see what the consumption for the specific trip was, but conservatively I'd say to go from 3.9 to 3.8, the consumption was at least 3.7 l / 100 km. This is better for the exact same trip which I have done several times. Using a lot of CC I have gotten around 4.3 l/100 km, so optimized driving makes the difference between 63.5 mpg and 54.7 mpg.

    The driving technique: The most important thing: at high load keep the ICE running in the upper half of the ECO HSI (high ICE efficiency). Don't exceed 80kph, and when climbing reduce speed so the HSI stays in the high efficiency zone (I went as low as 40kph at some steep 10% uphill sections.) Instead of constant speed, manage the HSI needle so you are in the upper ECO area. At mid-load use P&G and forget about trying to truly glide (pain in the nice person), go ahead and use the electric motor a little. If a substantial downhill or uphill is coming up, go ahead and abuse the electric motor carefully managing the HSI needle so it stays under the midpoint of the HSI (the idea is, we will get the recharge either at optimum ICE efficiency or for free via regen.) When using electricity don't go over 75kph so we don't spin the ICE. Naturally my P&G usually go to 80kph, lift, dip to regen and by the time the go pedal is pressed the speed is <= 75kph so we can go on pure electricity.

    Considering how hilly this route is, I'm stocked. It definitely pays to be looking at the electric motor for help when the ICE will be running inefficiently!
     
    Robert Holt likes this.
  2. HaroldW

    HaroldW Active Member

    Joined:
    Mar 17, 2012
    716
    94
    0
    Location:
    Grand Forks BC Canada
    Vehicle:
    2014 Prius
    Model:
    Three
    Excellent. The best I have managed is 3.0 ltr. Per 100 kil. For 43 kil out and return. Mountain area. I have a 2014. Gen 3. An love it. Keep up with your great fe. H
     
  3. Mendel Leisk

    Mendel Leisk Titanic Social Director

    Joined:
    Oct 17, 2010
    36,309
    25,116
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    If I think pure thoughts and sorta channel a hummingbird, I can sometimes nudge the trip meter (little relationship to calculated) down to 3.9 liters per 100 km. It doesn't last long though. Oh well.
     
  4. zebekias

    zebekias Member

    Joined:
    Aug 12, 2014
    100
    34
    0
    Location:
    Greece
    Vehicle:
    2010 Prius
    Model:
    N/A
    If you don't go over 80kph and focus on ICE efficiency, you'll be consistently at 3.9 or better.
     
  5. zebekias

    zebekias Member

    Joined:
    Aug 12, 2014
    100
    34
    0
    Location:
    Greece
    Vehicle:
    2010 Prius
    Model:
    N/A

    That's tremendous. What strategy do you use?
     
  6. HaroldW

    HaroldW Active Member

    Joined:
    Mar 17, 2012
    716
    94
    0
    Location:
    Grand Forks BC Canada
    Vehicle:
    2014 Prius
    Model:
    Three
    My strategy is cc and try to keep the ld. below 90. (scan gauge ) . Never in a hurry. I just completed a trip of 2450 kilometers and arrived home at 4.1 indicated. My average speed was 61 kph. H
     
    #6 HaroldW, Aug 24, 2014
    Last edited: Aug 25, 2014
  7. zebekias

    zebekias Member

    Joined:
    Aug 12, 2014
    100
    34
    0
    Location:
    Greece
    Vehicle:
    2010 Prius
    Model:
    N/A
    Now that I got used to high ICE efficiency driving I am getting a consistent 3.8 l/100km (indicated by the car) on round trips. The only problem is I'm driving slower than my usual cruise controlled 80kph because to "glide" on electricity you have to go 75kph or less, so I often do between 75-60 kph when the ICE is off. This works fine for secondary roads, the highway may be another story.
     
  8. HaroldW

    HaroldW Active Member

    Joined:
    Mar 17, 2012
    716
    94
    0
    Location:
    Grand Forks BC Canada
    Vehicle:
    2014 Prius
    Model:
    Three
    90 -100 kph normally nets me 4.1. Lots off long climbs hurts somewhat. Never seem to get it all back on the decent. Over all I am very satisfied with my gen2 3. H
     
  9. HaroldW

    HaroldW Active Member

    Joined:
    Mar 17, 2012
    716
    94
    0
    Location:
    Grand Forks BC Canada
    Vehicle:
    2014 Prius
    Model:
    Three
    Zebekias, what cost is a ltr. of petrol in your area. Here in British Columbia Canada we pay from $1.40 - 150 per ltr.. H
     
  10. Robert Holt

    Robert Holt Senior Member

    Joined:
    Aug 3, 2013
    1,278
    830
    0
    Vehicle:
    2012 Prius
    Model:
    Three
    Uh, I tried following the link to your map, but it was all Greek to me!
    In any case, congratulations on your achievement !
     
  11. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

    Joined:
    Oct 9, 2012
    1,166
    276
    0
    Location:
    Northern California
    Vehicle:
    2012 Prius
    Model:
    Plug-in Base
    Made me smile when I saw the map :)
     
  12. zebekias

    zebekias Member

    Joined:
    Aug 12, 2014
    100
    34
    0
    Location:
    Greece
    Vehicle:
    2010 Prius
    Model:
    N/A
    Google has really done a number, I go on maps.google.com and it insists on going to maps.google.gr they are too smart for their own good :)
     
  13. zebekias

    zebekias Member

    Joined:
    Aug 12, 2014
    100
    34
    0
    Location:
    Greece
    Vehicle:
    2010 Prius
    Model:
    N/A
    Prices have fallen recently, it's around €1.60 per liter right now.
     
  14. zebekias

    zebekias Member

    Joined:
    Aug 12, 2014
    100
    34
    0
    Location:
    Greece
    Vehicle:
    2010 Prius
    Model:
    N/A
    Hmm, now that I know how to get 3.8, I'll try speeding up a little to see what happens.
     
  15. bwilson4web

    bwilson4web i3 and Prime

    Joined:
    Nov 25, 2005
    22,784
    12,697
    0
    Location:
    Huntsville AL with 2014 BMW i3-REx
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    The map is perfect! I've ported it to Google Earth so we can see the elevations:
    greek_tour.jpg
    Based upon the elevations, I recommend:
    • Descend tallest slopes, >30-40 m, in "B" - this will minimize traction battery heating which can be severe in the Eastern part of the route. Since this turns off cruise control, shift between "B" and "N" on the descents to maintain an optimum speed. Use of "D" is OK but "B" and "N" are your best bets. A cooler battery is a longer lasting and more efficient one.
    • Starting from Eastern end on a 'cold start' (first use of the day,) start the car but let it idle until it shuts off the engine by itself, ~70 seconds. This means the engine and catalytic converter have reached self-tuning, mixture mode and the subsequent hill climb will be efficient. The Western section , cold-start is not so sensitive because it is level.
    When climbing, I like to use large trucks as a 'pacing' vehicle. It means a slow, efficient climb and following traffic will blame the truck for the slow speeds. <GRINS>

    GOOD LUCK!
    Bob Wilson

    ps. Don't make a fetish of this style of driving. But it has some solid engineering data behind it if you are interested.
     
    #15 bwilson4web, Aug 26, 2014
    Last edited: Aug 26, 2014
    HaroldW likes this.
  16. zebekias

    zebekias Member

    Joined:
    Aug 12, 2014
    100
    34
    0
    Location:
    Greece
    Vehicle:
    2010 Prius
    Model:
    N/A
    It's unclear to me how slow you have to go during the warmup cycle to be on the electric motor only. My indicator lies, it shows ICE is used even if I go one kph lol! I read if you exceed some magic threshold load it will use the ICE, yikes. So if I can't literally crawl at 15 kph for about 50 sec (this is how long warmup takes here with ambient temps > 30 C) I warm up stationary.

    Regarding battery heating, is it that big of an issue that it's better to get say 50% charge with light regen rather than 100% indicated (it's not truly 100% as we know) charge? On a 500m descend I often go through I definitely use B and still get a full charge by the time I'm down :) I guess it's better to get a slow regen charge rather than a quick one.

     
  17. bwilson4web

    bwilson4web i3 and Prime

    Joined:
    Nov 25, 2005
    22,784
    12,697
    0
    Location:
    Huntsville AL with 2014 BMW i3-REx
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    The engine has to run during warm-up so let it but at a minimum load. There are three critical temperatures:
    • ~50 seconds - the O{2} sensors start working and the engine controller can tune for an optimum fuel mixture.
    • ~40C - the engine can auto-shut at a stop or slowing down.
    • ~55C - the engine can auto-shut and use traction battery power when the load is low enough.
    But it turns out the first use of the day is the 'cold start' (not counting winters in Northern climates.) There is some residual heat that helps subsequent trips.

    Heating the traction battery was a problem with the first NiMH cells and modules. What happens is in hilly country, the descents cause exothermic, a chemistry based, heating. Then driving up the hills so hard that the traction battery charge is drawn down contributed resistance-heating. Do enough hills at high speeds and the traction battery can get not just warm but hot. To reduce heating:
    • Use "B" on descents and alternate with "N" and "D" to 'feet on floor' control the speed.
    • Back-off on drawing traction battery power ascending hills so it won't force unnecessary charging.
      • Use a heavy truck ascending a hill as a 'pacing vehicle'
    You might consider getting a Prius-aware scanner, one that reads the traction battery temperatures. This will let you see what is going on with more details than our mumblings in PriusChat.

    Bob Wilson
     
Loading...
Similar Threads - hilly rural terrain
  1. cpatch
    Replies:
    17
    Views:
    2,208