Power Split Device

Discussion in 'Gen 4 Prius Technical Discussion' started by dstahre, Jun 27, 2016.

  1. Jeff N

    Jeff N The answer is 0042

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    You are referring to a price goal stated by Bob Lutz in 2007.

    $30,000 in 2007 dollars is equivalent to $34,726.25 when adjusted to today's dollars based on the official US government consumer inflation index.

    CPI Inflation Calculator

    The starting MSRP of a 2017 Volt is $33,220 plus $875 for the mandatory destination fee which comes to $34,095.

    $34,095 is arguably "nicely under" $34,726.

    For that price you get a 53 mile battery range and 42 mpg on gas versus the 2011 Volt which had 35 miles of battery range and got 37 mpg on gas.

    GM could have chopped the 2017 Volt battery in half and spent some of the savings to pay for upgrading to the Malibu's gas powertrain and they would have likely ended up with a somewhat less expensive car that got 50+ mpg on gas and 27+ miles of battery range although with much better hybrid acceleration performance than the Prius Prime.

    Instead GM chose to focus on the electric side and distinguish the car from all of the other 20-something mile range plugin hybrids. I think they made the right choice.
     
  2. john1701a

    john1701a Prius Guru

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    You know very well the goal of $30,000 is still much required to be competitive.

    No excuses. No spin. No time.
     
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  3. john1701a

    john1701a Prius Guru

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    Sales determine that, not you and I.

    Remember, the goal is to replace traditional vehicles... quickly.
     
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  4. Jeff N

    Jeff N The answer is 0042

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    You seem to have your own personal price goal of $30,000 in 2017 dollars. That's fair.

    I was just pointing out that it isn't reasonable for you to take a price goal stated by GM exec Bob Lutz in 2007 during early stages of the Volt's development process and then pretend that a decade of inflation doesn't exist.
     
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  5. Jeff N

    Jeff N The answer is 0042

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    And just for the record, I think Toyota did an excellent job updating the Prius Prime. It's very competitive and provides excellent efficiency, a good price, and much improved battery range and electric performance. Toyota played to their strengths.

    Is the Prime the perfect car for everyone? No, of course not. Plenty of car buyers will be attracted to a Volt that has twice the range and stronger battery as well as hybrid acceleration although at a somewhat higher price point before subsidies. Some may choose for other reasons like aesthetic appearance or smartphone integration.

    Whatever. Choice is good. I'd much rather see a variety of vehicles that play to differing strengths than to see all plugin hybrids have essentially the same size, performance, battery range, and efficiency. That would be like a wall of cereal brands at the supermarket that were all slight variations of unsweetened Cheerios. I like Cheerios but I'd rather have choices.
     
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  6. Jeff N

    Jeff N The answer is 0042

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    Here are the sales numbers from InsideEVs for January, 2017, a typically slow sales month due to tax year timing for plugin credits.

    It will be interesting to see how the sales reports accumulate this year among the Volt, Prime, and Bolt EV among others.

    IMG_2508.jpg
     
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  7. Superior Monkey

    Superior Monkey New Member

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    I'm driving a 2016 Prius, and the only thing keeping me below 60mpg is heavy usage of the aircon. 52 sounds almost weirdly low, like I'd have to work really hard to get it that low. That would affect the comparison somewhat. And yes, I can see that Volt owners intend to stick with wall charging, if they wanted to use longer range consistently they would probably be in a different car. Even so, it seems to me that the efficiency gains of the Volt are rather outclassed by the Prius. The synergy drive just works so well.
     
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  8. Prodigyplace

    Prodigyplace Senior Member

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    They changed the EPA test to be more realistic. I regularly get more than 52. One city trip this week I got 74.
     
  9. bhtooefr

    bhtooefr Senior Member

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    @Superior Monkey: Are you using US or Imperial gallons?

    Also, winter in many parts of the US destroys efficiency in the Prius (especially on short trips, which I have a lot of), and in the US, a lot of people drive quite high speeds on the freeways. I'll have tanks that, through calculating miles traveled / gallons to fill the tank, average below 50 miles per US gallon, right now, and I'm averaging 51.5 so far: bhtooefr's Prius (Toyota Prius) | Fuelly

    Granted, some of those recent tanks were with damage to the front end of the car, but still.
     
  10. Prodigyplace

    Prodigyplace Senior Member

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    They were quoting the EPA rating. I almost made the same mistake.
    Highway miles, especially at higher speeds, greatly reduce MPG.
    Short trips, especially in colder weather are murder on MPG.
     
  11. bhtooefr

    bhtooefr Senior Member

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    Right, but they said that only air conditioning kept them below 60 MPG, which made me wonder if they were using Imperial (bigger) gallons.
     
  12. john1701a

    john1701a Prius Guru

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    It doesn't for the other vehicles. Notice how they all evolved to retain the same price-point?

    Why do you feel Volt is exempt from that same expectation?
     
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  13. Prodigyplace

    Prodigyplace Senior Member

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    Possibly. Singapore is much warmer than Ohio or Virginia.
    This morning with temperatures in the low 30s F my MPG was in the high 40s F
    The US has a wide range of temperatures from below 0 F to 100 F. that is a wide range to try and get a "real world" standardized test.
     
  14. bhtooefr

    bhtooefr Senior Member

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    The US's approach, by the way, is to do all tests at 75 ºF, except for the SC03 (high temperature air conditioning test) at 95 ºF, and a cold-temperature run of the FTP-75 test (which is normally at 75 ºF - the name has nothing to do with the temperature, it's a test procedure developed in 1975) at 20 ºF.

    Both city and highway mileage use FTP-75's warm-up stage, at 75 ºF and 20 ºF, to determine fuel economy impact by warming up.

    City mileage uses, in addition to warm-up, both FTP-75 at 75 ºF and 20 ºF, with the 75 ºF runs weighted by the city portion of US06 (a high-speed/aggressive driving test), as well as SC03.

    Highway mileage uses, in addition to warm-up, the HWFET cycle, the highway portion of US06, and SC03.

    Source: https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol31/pdf/CFR-2012-title40-vol31-sec600-114-12.pdf
     
  15. Superior Monkey

    Superior Monkey New Member

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    US gallons. Weather in the 77-92F range. Definitely not intending to compare that to a short trip-cold weather scenario, which definitely makes for bad mileage. Also hrm, my top highway speed is about 60, we don't have an equivalent of interstates here. It's a small island. I'd say I do a lot of driving around 50mph. In particularly hot weather I'm down to the low 50's mpg. I'm guessing the primary reason my results are so much better than the EPA tests is the lack of 70+mph driving? Wind resistance being highly nonlinear as speed increases.

    Edit: To get back on topic a bit, I feel like my numbers are proof of the awesomeness of the PSD design. In conditions that involve a *lot* of variable speed driving, speeding up and slowing down really frequently, I can drive with so little fuel consumed. Keeping the engine near optimal speed is quite the big deal, IMO.
     
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  16. RCO

    RCO Senior Member

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    That sounds like just moving the goalpost. Have you considered a career in politics?
     
  17. bhtooefr

    bhtooefr Senior Member

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    Not only the lack of high speed driving, but also the lack of cold weather driving - cold kills the mileage faster than AC, in my experience. So, you're not getting the 20 F mode warm-up penalty, that's factored into the EPA numbers, and you're not getting the high speed penalty on your highway numbers.
     
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  18. Trollbait

    Trollbait It's a D&D thing

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    The main cause for the Prius fuel economy advantage over the Volt in hybrid mode isn't due to the PSD, it is simply because the ICE is more efficient. Being 500 pounds heavier also doesn't help the Volt.
     
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  19. Jeff N

    Jeff N The answer is 0042

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    New cars in general go up in price with inflation just like everything else. I guess you are saying that a certain subset of cars have not gone up in price over the last decade? The Volt has dropped in price by quite a bit in 6 years while gaining a fair bit of range and some better performance and, yes, improved hybrid gas mpg.

    Still, the Volt has twice the range and much better acceleration performance compared to the Prime and similar plugin hybrids and those are qualities that people are used to paying extra for.

    It would not be reasonable for the Volt to be the same price. It's not a clone of the Prime and that's on purpose. We need a variety of plugin car models with different strengths so that people with different requirements can find cars that are a good match for them. Free market, choice, and all that.
     
    #79 Jeff N, Feb 3, 2017
    Last edited: Feb 3, 2017
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  20. bhtooefr

    bhtooefr Senior Member

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    Note that the Prime is only 200 pounds lighter than the Volt, and still beats the Liftback (although not the Eco) on charge sustaining mode MPG.

    First, let's note the mileage ratings for the cars in question:

    Prius Eco: 58/53
    Prius Liftback, 15" wheels: 54/50
    Prius Liftback, 17" wheels: 49/46 (based on this post - it's not an official rating)
    Prius Prime, charge depleting: 55/53
    Volt: 43/42

    However, the Volt has a ~0.28 drag coefficient, versus 0.24 for the Liftback, 0.25 for the Prime.

    In addition, the Eco, the Liftback with 15" wheels, and the Prime all use either Toyo NanoEnergy A29s or Dunlop Enasave 01s, in 195/65R15. (Allegedly, the Bridgestone Ecopia EP422 Plus is also an option in this size, but I don't think I've seen anyone mention having it in 15"?)

    The 17" wheel Liftback uses Bridgestone Ecopia EP422 Pluses in 215/45R17.

    The Volt only has a 17" size, Michelin Energy Saver A/S in 215/50R17.

    So, we know that the Liftback burns about 10% more fuel in the city, and 8.7% more fuel on the highway, with 17" wheels. Let's assume the Volt takes the same hit from its 17s, and give it those percentage improvements to downgrade to 15s... and now it's getting about 47/46, still with a lower thermal efficiency engine, more aerodynamic drag, and more weight as factors working against it.
     
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