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Playing With ‘24 PP XSE Mileage On The Interstate

Discussion in 'Gen 5 Prius Fuel Economy & Prime EV Range' started by Cc103acs, Jul 12, 2024.

  1. Cc103acs

    Cc103acs New Member

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    I went on a long drive in my ‘24 XSE Prime and decided to play around. Like most of the advice I see, if you have a prime and jump on the Interstate, just put it in Hybrid Mode. But… I had 45 miles of EV miles in my bank so I had the option of driving in EV until the juice ran out or doing something else. The route took me on I-90 from Albany east through the hilly Berkshire mountains, and then south on I-95 into Connecticut. I wondered what would happen if I did the trip in the Hybrid mode but only switched over to EV when I hit a downhill stretch. So after 3 hours of non-stop driving and using my EV mode to coast down hills and doing a bit of regen, here is what I came up with. Is this a more efficient way of driving on the interstates? The statistic that struck me is the 50% EV. Again, the trip was 167+ miles and I only had 45 mile of electric range showing on my “guess-o-meter.” View attachment 257148
     

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  2. Trollbait

    Trollbait It's a D&D thing

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    The EV ratio also includes the times the engine was off while HV mode. That said, I'm sure your EV mode miles went over the system's prediction. Did you make note of the SOC level before and after?

    Can't say if this is actually better. The car would turn off the engine while coasting down the slopes in HV mode. Switching to EV mode would be a more reliable way to keep in Ev operation instead of fine pedal control. Need to repeat the trip in just HV to see the difference. A thorough test would also repeat with leaving it in EV mode until the range was depleted, and even one with the EV range already gone.
     
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  3. Cc103acs

    Cc103acs New Member

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    I found myself gaining EV miles on the longer or steeper downgrades. I suspect the question is do I regen more in EV mode or HV mode. I am not repeating that ride anytime soon but I do have a 16 mile run to the store that I do frequently. Believe I will give it a go with a shorter out & back 32 mile format.
     
  4. vvillovv

    vvillovv Senior Member

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    Switching modes in a Prime has it's own set of rules. It's possible that switching to EV and gliding downstream can provide more regen. Best of luck trying to quantify the difference in regen on a 100 mile trip or longer switching modes. I can't wait to read your observations from your planned shorter trips.

    maps show Albany to Newton at 161 mi. Where in CT did your finish your drive?
     
    #4 vvillovv, Jul 13, 2024
    Last edited: Jul 13, 2024
  5. Cc103acs

    Cc103acs New Member

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    It was actually Schenectady to Essex, Ct and I basically went I-20, I-91, and Route 9… interstate all the way.

    As I thought about this, traveling in HV mode only has an EPA rating for the XSE of 47 MPG HV. I added in an EV only-element so my initial thought is this may be a more efficient way of doing interstate travel and could be helpful for those Prime owners who commute primarily via interstate.
     
  6. vvillovv

    vvillovv Senior Member

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    Thanks for the update, I'm interested cause I travel those routes too, last time to Mansfield late Nov 2023 and other times to Webster, Norwich or Deep River.
    The EV/HV thing in the Prime can be as easy as pushing the right button or letting EV range run out and letting the car switch automatically. The behavior can change quite a bit summer to winter and not just MPG wise. Having a routine that's repeatable under the same conditions can make it a lot easier to begin to understand what is going on when the car switches over. It's even more helpful if you can get the car to switchover at roughly the same place and/or time. Not many owners have the time or patience to feel out the car that way, but if you're into the MPGe thing there are lots of thing the Prime can show if given the chance.
     
  7. Zeromus

    Zeromus Member

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    Even if you don't switch to EV mode, I'm sure the car on a long drive will still do really well if it has EV range in terms of MPGe.

    I don't know if they test the MPG ratings for EPA with 0% SOC or not. But even in HV mode driving down the freeway for a shorter distance of 20-30kms, I find the EV mode kicks on when cruising quite often. And in traffic the EV mode kicks on and stays on for long stretches too.

    With the bigger battery it probably favours EV mode while in HV mode more than the normal prius would too. I mean, one can assume the normal prius with a smaller battery will have a smaller amount of "operation in EV mode" available so likely accesses it less often? Then again when in HV mode the car likes to target 75-80% SOC on the dash for EV reserve in HV mode. So maybe it does use the same algo as the regular prius when in that mode.
     
  8. RichFilmaker

    RichFilmaker Junior Member

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    Wow! That's GREAT for interstate highway miles. Couple of questions. Was the speed limit 70, and did you maintain it or go faster? Did you use cruise control? I've found that in my 2017 Prius II, I can get an avg of 60mpg in normal city/highway as long as I: 1. Use cruise control whenever possible (let the car do the downhill re-gening) 2. Do the speed limit.
     
  9. HacksawMark

    HacksawMark Active Member

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    I consciously switch between Auto/EV and HV mode when driving. On the highways/freeways, I always have it in HV mode with no need to switch to EV mode on downhill portion; the car will auto switch between HV and EV itself on those sections. When driving in the city or small towns, I switch to Auto/EV mode. Took a 60 mile road trip yesterday (120 miles total) to Corvallis and back using 99W and averaged over 67 mpg both ways.