Absolutely stunned at overall MPG with the new 2021 Prime!

Discussion in 'Prime Fuel Economy & EV Range' started by Thebakerman, Apr 2, 2021.

  1. Gokhan

    Gokhan Senior Member

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    To get the real mpg, you need to subtract your EV driving. The battery state of charge (SOC) typically decreases in HV driving, and you need to account for that. Also, the MFD inflates the actual mpg by 5–10%.

    All this said, my actual mpg is over 70 mpg. If I don't account for what I listed above, I typically see over 80 mpg on the MFD every time in HV driving. Warmer weather is pushing it over 90 mpg; so, the actual mpg is approaching 80 mpg in warmer weather.

    If I get caught in stop-and-go traffic, I get something like 115 mpg (over 100 mpg after the corrections listed above), which is amazing, easily beating motorcycles!
     
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  2. pakitt

    pakitt Senior Member

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    You get 80 in trips done exclusively in HV mode? And even 115 in HV only mode when in dense traffic? How?!?
     
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  3. Gokhan

    Gokhan Senior Member

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    I broke in the internal-combustion engine very slowly. Crawling freeway traffic is when the Prius Prime's HV fuel economy shines most. I do employ hypermiling techniques, trying to stay below 57 mph on the speedometer when I can.
     
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  4. Tideland Prius

    Tideland Prius Moderator of the North
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    80 isn’t hard if you’re not travelling at highway speeds. Including highway (90-100km/h), I got 73.5mpg
     
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  5. pakitt

    pakitt Senior Member

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    I guess I underestimate the hills around here and the elevation (2000m / 6500ft)
     
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Right I forgot you’re in CO. Never mind. Hills and mountains throw a wrench (although rolling hills can be good for mpg). My elevation changes are less severe than yours but I’m not in a flat area.
     
  7. Banksy

    Banksy Active Member

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    I get about 66 to 72 without a charge on the highway

    I can get about 34 miles on a plug in too.

    It really is an incredible car and I'm shocked thinking of what they will be like with solid state batteries
     
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  8. Gokhan

    Gokhan Senior Member

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    In Los Angeles, it is not hard to find a Prius Prime that has never been in traffic. My 2021 Prius Prime still had all the plastic protectors on it, clearly no customers had ever been in it, with only 4 miles on it from driving around the ports etc. This is important because test-drivers could stress and improperly break in the internal-combustion engine. I didn't even bother to test-drive it, as already had a 2020. After the paperwork was completed, I made the entire 17-mile trip home on surface roads, avoiding the freeways, so that the proper engine break-in would be initiated. in the first 1000 miles, I never exceed 55 mph. So, I think having bought an entirely virgin car and then breaking it in slowly helped me obtain amazing fuel economy.
     
  9. Thebakerman

    Thebakerman Member

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    Nice read. However I can tell you that unfortunately your wrong. There is 3 batteries in the prime. There is a lithium (for charging ev, there is the 12v battery (standard) and then the regular battery that all standard priuses have. Maybe 2 of them are located in the same area but still is 2 different batteries besides the 12v. Meaning one more battery aka ev lithium Panasonic made in addition. I can also tell you that by keeping a charge on the lithium ev battery that your mpg is alot better. For me personally a easy 10mpg difference. I get 53-55 on all ev ran out, just normal eco. Now when I have even just 10% ev left I get 63-65. Nothing is activated. Furthermore I have been driving priuses for over 12 years and this is my 6th.
    Really good read and write up for the most part. Unfortunately there is more than one battery in the Prius prime. There is three to be exact. There's the 12 volt, there's the EV battery, plus the standard traction battery that all standard priuses have. Fyi.

    Furthermore I've been driving Priuses for over a decade. I've had five to be exact. That being said when the Prius Prime isn't fully discharged as far as the EV battery it does give you much better mpg. I would avg 55ish with ev at 0%. Now with even just a 10% charge it n EV but driving in same mode, same route I can achieve low 60 mpg easy. However I'm usually in the 63-64 to be honest. So it does make a difference to say the least. Plus you get better torque and more electric mode usage having some ev juice leftover. I drive 2-300 miles a day. Tried every mode backwards..lol. That being said with ev mode on 1 full charge and leaving about 20% for the rest of the night, I avg 70-72mpg with about 200-250 miles on clock with just one charge daily. Using about 2.2-2.5 gallons of gas. Works for me. Way better then standard Prius in every way shape and form.
     

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  10. Thebakerman

    Thebakerman Member

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    I have 10k miles and avg 68 mpg on odometer. Only one plug in a day.
     
  11. Salamander_King

    Salamander_King Senior Member

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    Nop, Prius Prime has only two batteries. One lithium high voltage traction battery and one 12v regular flooded lead-acid battery. There are no separate batteries for EV and regular HV drive. It's all in one big battery, just a portion (about 14% of SoC) is reserved for the HV mode operation, the rest is used for the EV mode except the reserve portion which the car would not touch. Whatever you cited is wrong information on current models of Prius Prime. Maybe on per-production models, although this is the first time I have read it.
     
  12. Tideland Prius

    Tideland Prius Moderator of the North
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    That's incorrect. There is only one high voltage battery and the regular 12V battery.
     
  13. Banksy

    Banksy Active Member

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    Wasn't aware this was a thing

    Oops

    Drove mine with 54 miles on it (was brought from another dealer) 1200 miles over a 2 week period going to New England

    Had the car a month or so has 2400 miles

    Whoopsie
     
  14. jerrymildred

    jerrymildred Senior Member

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    As pointed out before, this is completely wrong. There is the 12V lead-acid aux battery that wakes up the computers and there is the 8.79 kWh traction battery. If there is enough charge in the traction battery, you can drive the Prime in EV mode. If the state of charge goes below about 23% actual (as opposed to what's on the display), the car goes to HV mode on its own. One battery, different states of charge.
     
  15. Thebakerman

    Thebakerman Member

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    Well this is my first Prius Prime and that's what you get when you take the salesman's word for it. Long story short, I do still get better gas mileage when I have percentage left on my EV battery versus when it's completely drained. Thanks for the video as well I love it
     
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  16. jerrymildred

    jerrymildred Senior Member

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    Understandable mixup now that you reveal your source. By and large, car salesmen are total ignoramuses. ;)

    There's a lot of debate about whether HV mpg is better with some range in the battery. It's practically impossible to prove one way or the other. Still, I'm also inclined to think that it helps. But it's not significant enough to be sure. It might be the weather or the phase of the moon. :D
     
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  17. Salamander_King

    Salamander_King Senior Member

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    The low threshold SoC for the EV-HV switch is more like 14% actual. I have checked the actual SoC of the traction battery using the Hybrid Assistance app as the EV range depletes as shown in the graph below. The 0-100% range on MID is actually 14%-84% SoC by HA.

    upload_2021-5-27_20-53-22.png
     
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  18. Gokhan

    Gokhan Senior Member

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    That's probably correct to some extent. In any case, the SOC never comes back to where you started during HV driving, which means you are always stealing some EV driving and cheating, but this is actually good for the environment. Typically, I lose about 5% during each HV trip. If you fully depleted your EV SOC allowance, the system would have to return what is borrowed and couldn't steal SOC anymore, which would hurt your HV mileage both directly and indirectly, the former because the system can no longer cheat and the latter happening when you don't have SOC available when the system needs it because the battery has been drained to the danger-zone limit.

    As a side note, I did witness the SOC coming back up to 1% or 2% after dipping to --, which I had thought never happened.
     
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  19. jerrymildred

    jerrymildred Senior Member

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    Interesting. I was going from memory from watching the videos by @john1701a. Seems like his car was switching to HV at 23%. I'll have to go back and check when I get some time unless he spots this and saves me the time. ;)
     
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  20. john1701a

    john1701a Prius Guru

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    When it dips below 14%, you see the switch from EV to HV.