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How will the Chevrolet Volt be better than a Toyota Prius plug-in hybrid?

Discussion in 'Chevrolet Volt' started by Adaam, Jan 31, 2011.

  1. austingreen

    austingreen Senior Member

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    I'm not quite sure why that would matter if true, he seems to have changed his mind about the car from here
    Jay Leno says he won't be rushing to buy Chevy Volt
    And chooses it over his other cars, and there are a lot of choices. Maybe he is choosing the volt because he wants to use electricity instead of gas. Leno is not by any means an environmentalist, but he is a car guy, and if car guys go plug-in that is a good thing.

    I wonder if the prius C will beat the original insight to number 2.
    They left out the tesla roadser at #2 with 111 mpge. WHat should be clear is the volt is more efficient than the EV1, as are the leaf, i-mev, and tesla. The electric cars not dead, plug ins have improved. I'm not sure where the prius phv will fall in this group.
     
  2. daniel

    daniel Cat Lovers Against the Bomb

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    I think that's misleading, because it assumes some "standard" mix of gas and electric. On my 300-mile-plus road trip up to Canada for hiking, my 2004 Prius will burn less gas than a Volt. The gasoline efficiency of the Volt depends on how far you drive it. Jay Leno apparently never needs to burn gas in his, so all the gas burned is WASTED to maintain the system which requires gas to be burned occasionally.

    When the Volt is burning gas, it burns more of it and puts out more pollution than the Prius. This, IMO, does not justify calling it the "most efficient gasoline-powered car."

    I'll bet the leaf uses less electricity per mile than the Volt in electric mode. This makes the Volt ideal for a very narrow range of driving needs, and mediocre for most driving needs.

    As for the iMiev, I'm expecting to like it, but comparing it to the Leaf is a bit unfair because the iMiev is so much smaller. OTOH, small is good, so I could well give it Daniel's Best-in-Class rating once I get a chance to drive one. The Chevy salesman promised to email me when they get a demo in. I'm looking forward to that.
     
  3. finman

    finman Senior Member

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    way to go GM!

    ...got a #1, most efficient vehicle built and sold...well...not as sold as they want. How this #1 rating competes in the efficient vehicle race is the bigger concern...too many cheaper, #3 choices out there. I really think too few will be able to sustain the Volt at $43k.

    Ok, what else ya got for me GM....b-4 I opt for a proven, pretty affordable base PIP at $31k?

    oh, not much. huh, that's not good. but a #1 efficient car and all the big gas-gulpers ought to prevent another bail-out. sarcasm.
     
  4. gwmort

    gwmort Active Member

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    Its a ranking based on EPA estimates, YMMV.

    I've found that my driving closely matches the EPA estimates pretty close, even the 60 mpge combined figure (when broken down to a common unit (BTU's)).
     
  5. Roadburner440

    Roadburner440 Member

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    This is why we use our Prius for road trips, and why it is with us now. I do miss driving the Volt though. Had to go to the dealer and drive their demo to get my fix... As far as the Leaf using less kwh per mile than the Volt from all my observations the Volt uses the same or slightly more kwh per mile than the Leaf. Granted there are a ton of factors that go in to that, but on my 12.9kwh I usually go 40 miles (I pick that number cause the lowest I get is 36, and highest I have seen is 47). Using my reading at my Kil-A-Watt meter that puts me at about 3mi/kwh for what it takes to charge it from the wall (12.9kwh).. Going by what the car actually uses (10.3) puts me at 3.88mi/kwh. Looking at the Leaf forum they are getting low 4mi/kwh mileage, but I do not know if they are taking into account the charging loss or not in those figures. I do not think the Volt gets to much less than the Leaf though. Going off this thread: My Nissan Leaf Forum • View topic - I Beat EPA's 2.9 Miles/KWh : Report Your Monthly Mileage they appear to be getting 3.2mi/kwh at the wall, and 4.1mi/kwh out of the car charge itself.. Not bad for us Volts lugging around an iron block 4 cylinder parasite under the hood. Of course though in that thread there are high's and lows from that guys baseline, but he seems about average like me with his usage.
     
  6. austingreen

    austingreen Senior Member

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    I don't think the EPA should try to guess what Daniels standard trip is, and put that on the sticker. YMMV, and from the on star reports the EPA standard uses a higher percentage of gasoline miles than the typical volt owner drives.

    YMMV. volt is the most efficient commerical phev out there, because its the only one. When Toyota, Ford, and Hyundai start shipping theirs we may see one be the most efficient gasoline powered car, but the typical volt owner is going to beat the prius owner if you are going to calculate mpge the way the epa does. Other discussions on how gasoline is really better than electricity are all through this and other threads.
     
  7. luckyboy

    luckyboy Member

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    I'm very dissapointed with the prius plug in. The battery capacity is only 1/3 that of the Volt. With the prius starting at $32K and I see the Volt being sold for $2-4K off their MSRP, you get 3 times the EV capacity in the Volt for only a couple grand more after tax credits ($2500 vrs. $7500). My commute is only 12 miles each way, but its only reasonable to assume the battery of the Volt would last much longer if it goes through less charge cycles than what would be required of the prius, all things being equal on the battery technology.
     
  8. john1701a

    john1701a Prius Guru

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    First, keep in mind that the battery in Volt gets worked harder. The one in Prius will be protected by the engine providing power when high demand is called for. Volt enthusiasts spin that as a weakness. Those seeking longevity think otherwise.

    As for the marked down prices for Volt, why do you think that might be?

    It's already looking like GM is coming to terms with having missed the mainstream target pricing of $30k by so much. There's talk of a scaled down plug-in system for Cruze now.
    .
     
  9. usbseawolf2000

    usbseawolf2000 HSD PhD

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    You are not buying the battery pack but the entire car. Why not just look at the entire package?
     
  10. gwmort

    gwmort Active Member

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    I agree, there is no single factor that should control your decision.

    Price isn't the great divide between the two it was earlier thought it would be. I'll bet efficiency won't be drastically different either overall. Whichever may be crowned mpg king isn't really relevant anyway as personal driving conditions and needs will have a wide sweeping effect.

    I'd say the biggest factors should be space (if you need that 5th seat the Volt won't do) and how you like the way it handles (if you drive a Volt and prefer the handling of the prius more power to you).
     
  11. usbseawolf2000

    usbseawolf2000 HSD PhD

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    I'd say commute pattern and carbon footprint from local grid are also big factors.
     
  12. SageBrush

    SageBrush Senior Member

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    How *is* the Volt better than a PiP ? Well, it apparently catches fire easier.
     
  13. Jeff N

    Jeff N The answer is 0042

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    The PiP can draw up to 27 kW from its battery pack, according to Toyota. If that were drawn against all of the cells in the 4.4 kWh pack, it would be:

    27 kW / 4.4 kWh = 6.14

    The Volt can draw up to 111 kW from its battery pack, according to GM. Since that is drawn against all of the cells in the 16 kWh pack, it is:

    111 kW / 16 kWh = 6.94

    To put this in context:

    6.14 * 16 kWh = 98 kW = 131 HP

    The maximum HP of a 2nd gen Prius is 110 and a 3rd gen is 134. So, when a Volt battery pack is being pushed as hard as the PiP battery pack at its maximum output of 27 kW then the Volt is putting out essentially the full 131-134 HP of a 3rd gen Prius.

    How often does a typical driver stomp a 3rd gen Prius accelerator pedal to the floor? Almost never. It's just uncommon to need all 130+ HP in normal driving. Typical driving rarely calls for more than 60 kW (brief acceleration on the highway) and normally much less.

    When a PiP battery pack is being pushed similarly hard it is only putting out 27 kW or 36 HP. How often does a typical driver press the accelerator pedal enough to generate 36 HP? Frequently. That much power is typical of normal acceleration in everyday driving by many people. The same power requirement on a Volt battery pack is much less stressful since the Volt pack is 3.6 times larger than the PiP pack. For the Volt, 27 kW is easy. For the PiP, 27 kW (36 HP) is relatively hard. Driving without gas is fun and so I believe that many PiP drivers will learn to drive in ways that maximize battery output without causing the gas engine to be started.

    Battery cells can be designed to optimize energy density versus power density. Presumably, the PiP cells are optimized for high power output. The Volt cells are reportedly optimized for power output as well but we don't know the detailed characteristics of either of the cell designs.

    The PiP battery pack has been described as consisting of multiple sub-packs which are drawn upon individually over time. This implies that the output strain on the sub-pack cells may actually be higher than described earlier since the load would not be spread evenly across all cells as it is in the Volt.

    It is also fair to assume that the PiP's much smaller battery pack is more likely to be recharged multiple times per day. Studies have shown that this is inherently harder on a battery pack than just charging overnight.

    As I said, some of this can be compensated for by battery chemistry and construction trade-offs although we don't know that it actually was (versus the Volt cells). Overall, these facts do not support your theory that the Volt battery pack "gets worked harder". The opposite seems more likely to me.
     
  14. john1701a

    john1701a Prius Guru

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    The demands of real-world make it a 6-of-1, half-dozen-of-another issue. Some of it may come down to software too. Isolating draw to a subpack could easily make it harder, but there's the ability to handoff to another to allow for rest & cooling. It would make when the engine joins in so flexible it's much more difficult to identify trigger conditions. We'll find out...
    .

    That depends a lot upon the consumers. Enthusiasts of Volt have sought out public charging-stations to avoid depletion-mode, immediately starting the recharge upon arriving at their destination. Prius owners are typically more of the "just drive it" type.

    Of course, how long of a empty soak makes a difference anyway? With a recharge time of just 1.5 hours from a 240 connection, you could have at least 6 hours of rest while at work prior to beginning the recharge.

    But then again, the Mall Of America is already offering charging-stations and you could easily see those patrons starting the recharge immediately. I won't... since I live just a few minutes from it and likely will still have plenty of SOC left upon arriving there.
    .
     
  15. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Actually, PiP can draw 38kW from the battery, perhaps for a brief moment. The gas engine could come on to protect the battery. Volt (being a heavier car) can climb a mountain with power only from the battery (and lugging around the gas engine).

    Hybrid Synergy Drive in PiP allows both the gas engine and battery to work together as a team covering each other's weakness. That makes the entire hybrid powertrain more reliable.

    Volt doesn't have the synergy drive.
     
  16. daniel

    daniel Cat Lovers Against the Bomb

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    Don't forget to factor in Toyota technology and quality control against GM technology and quality control. I'd put Toyota miles above GM on both counts. I would not assume that battery technology, quality, or control would be equal.

    Correct! The EPA should provide two separate figures: miles per kWh in EV mode, and miles per gallon in CS mode. That would allow cost-per-mile comparisons for any given mix.

    As I understand the PiP (and I'm open to being corrected) the additional battery capacity (over and above the non-plug Prius) is switched off-line once it is depleted. I think this is a big mistake. Allowing the full battery to be used would provide more head room for long downhill regen, and more available electric energy for long uphills. I recall in the very early days of Prius, when one adventurous soul (I forget who) added an extra battery pack and logged an improvement in FE just by having the extra capacity. This was not a plug-in. It was just a bigger buffer.

    If Toyota is going to spend the money (and charge consumers for) a larger battery pack, they should allow the car to make full use of it. JMO.
     
  17. usbseawolf2000

    usbseawolf2000 HSD PhD

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    That was true for the prototype PHV but false for the production model.
     
  18. daniel

    daniel Cat Lovers Against the Bomb

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    Are you saying that the production PiP does allow full use of the battery after the grid charge is depleted? That would be a very good thing.
     
  19. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Yes, Prius Experts said the production version will be able to regen back to full from empty.
     
  20. gwmort

    gwmort Active Member

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    I believe what they said is that it would not limit the amount of regen to a preset level so that no regen energy would be lost while there was still capacity to store it.

    I think what you'll find is that regened energy will be consumed before other available energy sources until the charge is returned to the charge sustaining level. Thats basically how synergy drive works anyway, you get a little regen slowing down then use it as you speed up again.

    I don't think you'll be able to keep socking away the juice from regen to use at one shot later. (I don't think there is a way to force synergy drive off and ONLY use the ICE, and if there is I doubt you'll get anything like hybrid level fuel economy while doing it).