1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Best Techniques to Drive the Prime

Discussion in 'Prime Fuel Economy & EV Range' started by inferno, Jan 13, 2017.

  1. inferno

    inferno Senior Member

    Joined:
    Jun 23, 2013
    1,072
    405
    0
    Vehicle:
    2010 Prius
    Model:
    III
    Ok...I'm still trying to figure this out on my daily commute. One thing I gotta say is, throw all conventional wisdom out the darn window.

    • 36-42 degree weather (getting cold again!)
    • 103.mpg for 49 miles.
    • Those same miles in my PiP was around 55-60 mpg in this weather.
    • 67% EV usage.
    • 3.1 miles EV left (shame on me!)
    This time around I drove on my big hill up all EV (which got me around 2-3 miles per kWH. Then on the steep decline for about a mile, turned on the Charge mode, maintained around 75-99mpg as I breaked and let the engine charge the battery. It went up 2-3 miles EV. Then I mixed my EV and HV driving, being a little harder on the acceleration for EV. This car's EV acceleration is great.

    Now with the PiP I got the best MPG by accelerating hard in HV mode, letting the engine pull the car. The Prime seems the opposite, better EV acceleration vs HV? What's also funky is that when I reached the top of the hill I had around 19 miles EV left. The PiP would run out of EV about 3/4's in.

    I started 33.8 miles EV this morning (bite that Gen 1 Volt!). My average kWH per mile (I like this figure now) is around 4.7 - 4.8 miles.

    So begs the question. HV suffer mpg on acceleration? Or EV suffer? For the PiP the HV was more efficient. But this may not be the case here!?

    DR;TL
    IE, the kWH per mile hit might give you better overall mpg in the end and use less gas on a Prime. Oh yeah, I should try this next time without Charging down hill...

    My previous best on this drive has been around 88 mpg.
     
  2. Pizza Driver

    Pizza Driver Active Member

    Joined:
    Oct 14, 2016
    158
    156
    1
    Location:
    United States
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    If the engine is cold at the top of the hill, I would put it into HV mode rather than CHG mode. The engine will go into its warm up cycle which will slightly charge the battery without putting any load on the engine while it is still cold.
     
  3. inferno

    inferno Senior Member

    Joined:
    Jun 23, 2013
    1,072
    405
    0
    Vehicle:
    2010 Prius
    Model:
    III
    I would gain maybe 10-20 mpg more? but 1-2 EV less? Maybe it is better, so many scenarios to try lol.
     
    JamesBurke likes this.
  4. huskers

    huskers Senior Member

    Joined:
    Aug 21, 2005
    2,542
    2,485
    0
    Location:
    Nebraska
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    My head hurts just reading that.
     
  5. Since2002

    Since2002 Senior Lurker

    Joined:
    Nov 12, 2011
    936
    1,097
    0
    Location:
    Duluth, GA
    Vehicle:
    2006 Prius
    Model:
    N/A
    I think Pizza Driver was referring to engine life, not mpg. Avoiding putting too much load on an engine until it reaches operating temperature. Some of us are old-fashioned that way.
     
    thatoneraccoon likes this.
  6. inferno

    inferno Senior Member

    Joined:
    Jun 23, 2013
    1,072
    405
    0
    Vehicle:
    2010 Prius
    Model:
    III
    There was a thread that mentioned this somewhere. Weather to let the engine warm up. I think even Toyota said it didn't matter with the prius. Just go and drive even in 0 degree weather.
     
    Arctic_White likes this.
  7. Since2002

    Since2002 Senior Lurker

    Joined:
    Nov 12, 2011
    936
    1,097
    0
    Location:
    Duluth, GA
    Vehicle:
    2006 Prius
    Model:
    N/A
    Not so much whether to start driving immediately but about putting load on the engine while it is cold. I just remember that was always the advice back in the old days with cars, a lot of people thought they needed to warm up the engine to operating temperature before they started driving, but the advice was no, wait a few seconds to get oil pressure but then start driving, drive normally, but avoid hard acceleration for the first mile or so. Now in an HV a lot of that acceleration is coming from the electric motor so it's probably not as critical, maybe not enough to worry about anymore. But hard to break old habits which is why I said some of us are old-fashioned about it. Coming out of my house I have an immediate uphill stretch of about 1/8 mile, on cold days I tend to baby it up that hill unless someone is behind me. Maybe I don't need to but I do it anyway.

    But one habit I had no problem breaking was waiting for oil pressure. When I got my first Prius I remember it seemed like such a luxury to push the button and immediately start pulling out of the driveway even before the ICE starts.
     
    Arctic_White and thatoneraccoon like this.
  8. Pizza Driver

    Pizza Driver Active Member

    Joined:
    Oct 14, 2016
    158
    156
    1
    Location:
    United States
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    When the ICE is on but the throttle position is lower than the half way point in the ECO section of the hybrid system monitor, then it will actually be charging the battery. This is why I recommended not going into HV mode until reaching the top of the hill. Use the battery to climb the hill, then when you get to the top of the hill, go into HV mode and the engine will kick in to start warming up even if it is not needed to drive the car. This will allow all of its energy to be used to charge the battery giving you more EV range for later in the trip.
     
    Since2002 likes this.
  9. Since2002

    Since2002 Senior Lurker

    Joined:
    Nov 12, 2011
    936
    1,097
    0
    Location:
    Duluth, GA
    Vehicle:
    2006 Prius
    Model:
    N/A
    Thanks for clarifying. Okay so I guess there is only one old-fashioned person (me) who still worries about putting a heavy load on a cold engine.
     
    thatoneraccoon likes this.
  10. Pizza Driver

    Pizza Driver Active Member

    Joined:
    Oct 14, 2016
    158
    156
    1
    Location:
    United States
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    From my experience in the Prius C, Toyota's software already accounts for mitigating the load on a cold engine. When I would start up with a cold engine you would see an incredible amount of drain on the battery even with low to moderate acceleration. I assume this was to take some of the load off the engine. I have not really seen this same behaviour in the Prime, but it would be harder to notice with its much large battery.
     
    thatoneraccoon likes this.
  11. Neohippy

    Neohippy Active Member

    Joined:
    Oct 29, 2016
    220
    201
    0
    Location:
    Clearwater,Fl
    Vehicle:
    2013 Prius Plug-in
    Model:
    Plug-in Advanced
    I agree with you. I don't drive the car very hard either until the engine warms up.
     
  12. Since2002

    Since2002 Senior Lurker

    Joined:
    Nov 12, 2011
    936
    1,097
    0
    Location:
    Duluth, GA
    Vehicle:
    2006 Prius
    Model:
    N/A
    That's good to know. I guess then the only time you would even think about it in regular Prius is if for some reason you didn't want to overly drain the HV charge in the first mile, so you would drive a little easier while the engine is still reaching full temperature. Of course in the Prime you are most likely starting out in EV mode anyway, which would seem at first to make this a moot issue, but actually it's just kicking the can down the road, because say 25 miles into your trip the cold ICE is going to start up. Do you want that to happen while you are climbing a hill? Maybe not, and I guess you could plan ahead about switching earlier to HV. But then again maybe it's not worth worrying about if we're only talking about a small inefficiency during a very brief period, as opposed to cumulative engine wear which is what I was thinking about. But even engine wear is probably not the worry it used to be, since with Prius it seems the engine will far outlast the car in most cases. Which I suspect will be even more true with PHEV.
     
  13. Rmay635703

    Rmay635703 Senior Member

    Joined:
    Oct 16, 2016
    2,567
    1,595
    0
    Location:
    Somewhere in Wisconsin
    Vehicle:
    2013 Chevy Volt
    Model:
    N/A
    IMG_2014.JPG I have never driven a Prime but I have always driven an EV.

    Every EV I have ever driven it's always more efficient to drive in ev at the lowest speeds possible, regardless of terreign.
    My volt is no exception, having a gas engine adds a dynamic especially in cold but it's still slow = ev fast= gas
    See my attachment below on my 2013 of what's possible if you optimize your route for low speed.
    It's a trip that's 1/3 low speed country, 1/3 high speed freeway and 1/3 medium speed country.
    With a gas engine on board it's a good idea to keep a small amount of electric range for high speed downhill (low load) situations but generally , especially in cold you want to keep heat off and engine off during ev, then isolate gas usage to occur all in one stretch.

    Aka you want to minimize longer gas engine on off events because efficiency drops a lot as your motor cools below 180 and falls off a cliff below 150.

    If you can provide the distances, speed and terreign of each "leg" of your trip I can give you a itinerary of when where and what.
    You need to pay close attention to your instaneous kw and remaining battery so you don't come home with more than a mile or so in the tank.

    Best thing you can do is set a kwhr/ mile goal and hold your instantaneous usage there as much as possible.

    Good luck
     
  14. inferno

    inferno Senior Member

    Joined:
    Jun 23, 2013
    1,072
    405
    0
    Vehicle:
    2010 Prius
    Model:
    III
    Now I'm confused. So at top of the hill it's worth switching to hv? Or should I stay in hv to climb the hill like in the pip? I guess jury is still out there. The cold factor doesn't help...
     
  15. Rmay635703

    Rmay635703 Senior Member

    Joined:
    Oct 16, 2016
    2,567
    1,595
    0
    Location:
    Somewhere in Wisconsin
    Vehicle:
    2013 Chevy Volt
    Model:
    N/A
    I don't think the hill really factors in as much as you think.

    If roadway speeds are low or if traffic is so light you can do whatever you feel like I would just drive electrically up and down the hill setting a kw/mile goal and include that stretch in your ev run and let the car turn on the gas burner when it wants

    The key is to know your route, optimize it then map it out into segments so you don't need to on off the engine as much.
    You will find on a predictable route you can approach the trip more analytically and adjust behavior to match the mode your in for that stretch.

    On my once weekly long trip I only have 3 sections even though it's a 100 mile trip, gas burn is on the middle 3rd and I focus my effort less on engine control and more on hypermiling technique
     
    #15 Rmay635703, Jan 14, 2017
    Last edited: Jan 14, 2017
  16. inferno

    inferno Senior Member

    Joined:
    Jun 23, 2013
    1,072
    405
    0
    Vehicle:
    2010 Prius
    Model:
    III
    There must be best practices some where. My Prime definitely did waaaay better on the uphill than my PiP. So the question is, 2-3 kWh per mile uphill or 25-30 mpg gas......lol. I guess it's all trial and error every day. But the strategy must change a bit during the extremely cold days.
     
  17. Tom_06

    Tom_06 Active Member

    Joined:
    Jan 10, 2006
    609
    140
    0
    Location:
    Newark, Delaware, USA
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    The Prime runs a loop of engine coolant to suck heat off the catalytic converter. The catalytic converter gets HOT in seconds, so this will help to warm the engine faster but they have to limit it so the catalytic converter can maintain the temperature it needs to work correctly. I do not know if the Gen 4's have this feature.

    Remember the 2004 generation Prius when it would store heated coolant in a thermos bottle and return it to the engine when you powered up? My 2006 had that but parking all day outside on freezing cold days cooled it to the point where it never helped much.
     
    thatoneraccoon and Since2002 like this.
  18. PT Guy

    PT Guy Senior Member

    Joined:
    Nov 23, 2016
    1,074
    707
    0
    Location:
    Washington, the state
    Vehicle:
    2017 Prius Prime
    Model:
    Plug-in Advanced
    Inferno, what is your mpg for the trip if you just switch the car into EV Eco mode and drive it? Do nothing fancy, just drive it? The only manual action will be to switch into B mode if there's a steep downgrade, and back to D mode at the bottom.
     
  19. inferno

    inferno Senior Member

    Joined:
    Jun 23, 2013
    1,072
    405
    0
    Vehicle:
    2010 Prius
    Model:
    III
    Taking a look at my original post:
    • 36-42 degree weather (getting cold again!)
    • 103.mpg for 49 miles.
    • Those same miles in my PiP was around 55-60 mpg in this weather.
    • 67% EV usage.
    • 3.1 miles EV left (shame on me!)

    I did the same thing with nothing special, no controls manual controller whatsoever.
    • 34 degree weather
    • 104 .1 mpg, 49.1
    • This technique yielded my PiP 50-52 MPG.
    • 68 % EV Usage
    • No Miles Left EV
    Other observations:
    • Got 18 miles EV including huge uphill grade. My PiP gave me 6 miles EV, the EV driving is extremely more efficient.
    • I'm not sold that "doing nothing" gives you the best MPG, look at the above, yes it's lower MPG but I had 3.1 miles EV left.
    • One thing to think about when you drive is to definitely use up your EV range, but ALSO use up your HV battery range, that's an extra few miles EV which is what the car is good at, efficiency in HV mode also.

    Jury's still out there. I'll do the same drive but Charge on my downhill with ChargeMode on.

    One other thing I noticed. I used to do HV only on the uphill, then on the top hill turn to EV. In the Prime the engine usually turned on, and I'm not sure why, although it would initially start in EV. Today, driving the entire hill in EV the engine never turned on going downhill. Some black magic is going on behind the scenes.

    Overall, is it worth it to "play" and toggle the modes? lol...with such small differences, maybe time will tell!

    I do think EV Auto may be the best of both worlds, ie, give you the best "push" for your EV range, although the threshold seems to vary quite widely.
     
    Tideland Prius likes this.
  20. inferno

    inferno Senior Member

    Joined:
    Jun 23, 2013
    1,072
    405
    0
    Vehicle:
    2010 Prius
    Model:
    III
    Do we have a winner?
    • 34 degree weather
    • 115.9 mpg, 49.1
    • This technique yielded my PiP 54-56 MPG.
    • 73 % EV Usage
    • 44 MPH Average Speed
    • 1:07 elapsed time
    • No Miles Left EV

    FYI Previous trip was 46 MPH Average and 1:03 elapsed time.

    Today's technique: Use the HV mode for steep upgrades. Any push in EV mode past the middle I'd switch to HV mode.

    Tomorrow - will test the same route using Charge Mode. Perhaps you guys are right, Charge Mode really won't do much. We'll see...