Prius Plug-in vs Chevy-Volt thoughts

Electrons are fungible. They always come out of wires in in my garage, and are mixed on the way from many sources. But since the country wastes THW of night time wind, because they cannot sell it, chances are really good that I'm getting what I'm paying for when I'm paying for it.

I bought green electricity before my volt and buy it for all of my power. But I can only buy what I use. I shifted my power from gasoline to renewable electricity.

 

...and not to mention looks good in the parking lot at sky parties. My Dob is Orion too. Better get red Prius for night vision. I wish you luck on the vehicle. I am wating a few years as my "fleet" is still young having taken tax credit opportunites for Hybrid and C4Clunkers. I can't fault those who like the tax credits, I do too.

 

iMev, Leaf, Tesla are all use much less gas. All have much better MPGe so in NG dominated grid areas (like Cali) (or with renewable power) are more efficient. If the Volt has enough EV% it is also.

 

How? Electron from renewable source is more expensive than one generated from coal. How can electrons be fungible if the price is different?

 

Big Macs in my area and in NYC vary greatly in price but are otherwise indistinguishable.

I'm generating about 40kwh a day right now in March emission free at home, using less gas and skipping upstream electric emissions makes my Volt much cleaner than a PIP.

 

They are fungible because once produced they are indistinguishable.

People do have to pay more to get renewable electrons produced, but the price of progress is not always cheep. The Volt costs a little more, and so does the power. Those of us that can afford to do so, can choose to pay a bit more, just like the earlier HV buyers payed a bit more.

 

iMiEV (30kWh/100mi), Leaf (34kWh/100mi) and Roadster (30kWh/100mi) use more electricity than Prius PHV (29kWh/100mi). Why are you comparing EV electricity consumption to PHV gas usage?

:focus:

Away from national average and back to Rebound specific case. Per EPA beyond tailpipe emission calculator, Volt's total emission would be 190 g/mi in the Bay Area.

So in the Bay Area, Volt is greener than the regular Prius. The original question was if the Volt is greener than the Prius PHV. Using the Bay Area electricity, Prius PHV should be in the same ball park (190 g/mi). So there is no clear winner. Both are just as green from what I can tell.

Volt get there by brute force with bigger battery. Prius PHV achieved the same by being more efficient when running on either fuel. Volt approach costs more, make the car heavier and provide less interior volume.

If we look at the national average level (both will be sold in all states), Prius PHV is the greener plugin.

One has green credit and the other doesn't. They are clearly distinguishable.

 

The prius PHV is only 95MPGe, all the other cars a much better.
This is the Nth time you misrepresent the data. The Prius PHV 29kWh/100 is only part of power used, you have to include the .2 gallons. There is a reason that EPA reports MPGe as that balances all power sources. Are you that dense that you still don't get that you cannot use just the EV power usage of the EPA test and ignore the gas energy. The PHV is slightly better than the Volt, using the EPA 60% EV, but if the EV% goes higher the volt can be more efficient if the driver us more EV than 2x the a Prius PHV drivers EV %.

Volt 190, Prius 222. Prius PHV will probably be about 215, which is 13% higher.


If you look where HVs are and Volts are likely to sell well, they will dominate sales in "green" states like Cali and not sell as well in dirty states. So where they sell, the Volt will likely be greener. And as I've said dozens of times, those who buy "to be green" can always buy green power like I do.

Yep the volt gets there with a bigger battery. The Prius PHV does not achieve the same thing, it achieves the same efficiency for less than 1/3 of the distance. If you are too poor to afford a Volt, then a new car is probably not a good option. If you need 5 seats I agree the Volt is not an option. But for many people the volt is far more efficient.

 

Sorry if I frustrated your life.

We'll have to see the number when fueleconomy.gov add Prius PHV. I think it is going to be very close, if not lower than the Volt.

You have a good point. We are comparing a 5 seater midsize to a 4 seater compact.

 

To be honest, the Volt at its post-federal-and-state-incentive price gave me pause about the Prius Plug-in. It would give me more than enough EV range for most of my driving, but the fact that after EV ran out it would have comparable mileage to a regular ICE compact car bugged me. Then I sat in one and decided I definitely did not like the size, comfort, or design.

While the Prius Plug-in has more limited EV range, I understand the engineering design decisions behind it. That's important to me as an engineer. Toyota gave the Prius Plug-in as much EV range as they could while making minimal compromises from the Prius Liftback platform the Plug-in started from. The spare was lost, but in 8 years of driving the Gen 2 Prius, I never used it, so no skin off my nose. And while I think Toyota made some missteps with the Gen 3 Prius, overall I think it was a good evolution of the Gen 2. The Gen 3 wasn't enough for me to upgrade my Gen 2, but the Plug-in added enough to justify upgrading. Toyota took a great concept, a very efficient midsize vehicle with the exterior dimensions of a compact, and made it better.

On the other hand, I don't understand the engineering decisions of the Volt. GM claims it is an EREV and it is, but IMO it was a brute force design not an elegant design. Tack on a big battery to compact car is what it appears to me to be. They presented the idea of a series hybrid, but actually built a parallel/series hybrid with a larger battery. A true series hybrid doesn't need the engine attached to the wheels mechanically, with or without a clutch. This means that the electricity generation could have been done with something much more efficient than a ICE; it could have been done with a microturbine. A microturbine would have been lighter, smaller, removed the need for the clutch to engage/disengage the parallel hybrid portion of the drive train, and generated electricity more efficiently. Being lighter would have increased the EV efficiency of the Volt, which in turn would allow smaller/less expensive batteries, reducing cost. A smaller generator and batteries would have allowed the Volt to be a 5 seat midsize instead of a 4 seat compact. Removing the clutch would have removed unnecessary complexity and saved additional space. Why GM chose to build the Volt the way it did boggles me. They had the opportunity to build a car from the ground up and instead of choosing to build a truly interesting car, they designed a car with unnecessary compromises in utility and efficiency.

When I took a step back and compared the two cars without the tax incentives, it became much clearer. I preferred the Prius Plug-in to the Volt. The tax incentives confused my preference temporarily, but the point of those incentives are to get buyers who normally would not buy an PHEV/EV to buy one. IMO, the tax incentives shouldn't change a person's decision on which PHEV/EV to choose.

Neither one is quite the PHEV I want, but the Prius Plug-in has less compromises than the Volt for me. I am hoping that EV chargers will proliferate, which will make the limited EV range of the Prius Plug-in less of an issue. I think the next generation Prius Plug-in will be the PHEV I really want and in the meantime, the current Prius Plug-in will tide me over.

For me, the only thing the Volt has over the Prius Plug-in is EV range. And I'll admit, it's not a small thing.

 

Having followed the history of Volt from Two-Mode origins, it's easy to understand. Business desire was where the compromise came from. Engineers were impaired by what marketing had already started to promote. In other words, they backed themselves into a corner very early on.

It was a commitment doomed by unrealistic expectations. Promises of outperforming the competition blinded decisions. Cost was allowed to increase without concern.

The first evidence of that I can recall was the decision to abandon the custom-designed engine and just use one from a traditional vehicle instead. The claim was to keep price low, but the efficiency penalty made you wonder. It contributed to the enthusiast focus on acceleration & power. GM thrived on the resulting hype. Focus was lost. Things fell apart from there.

Bringing up the topic of cold-temperature influence confirmed constructive discussion was no longer possible. Hope had taken control, long before the design had even been finalized.

Later, when it was leaked that Volt wasn't actually a serial hybrid as promoted, it started to get ugly. Information about depleted efficiency was withheld, despite countless enthusiast requests. Then came the price announcement. That was the beginning of the end. Before rollout, there was disenchantment among supporters. So as owners began to report real-world data, it was already too late. The damage had been done and each attempt to repair only ended up making the situation worse.

Now, we have the first PHV arrivals. What does that mean for Volt marketing? What about design? What about sales? This certainly is an interesting time in automotive history.
.

 

This graph is wrong. It shows as if the Prius does only 45mpg. C heck where Prius' line crosses 1 gallon and substract those miles with 15 miles, where Prius' line begins.

 

This graph is wrong. It shows as if the Prius does only 45mpg. heck where Prius' line crosses 1 gallon and substract those miles with 15 miles, where Prius' line begins. It also shows as if Volt does 38 miles on electricity.

 

Comfort is important.. so if you don't like fit that is reason enough for the choice.

But your comments about the engineering surprises me. I dug deep into the engineering and was pleasantly surprised at the Volt design. I'm amazed at how many arm-chair engineering efforts say it would be more efficient to do X. Good engineering is hard and good engineering includes understanding costs and usage.

A long time ago I had done a Serial PHEV design so understood some of the limitations. Unlike some purists who were unhappy to learn the volt would, on occasion, be a parallel-series hybrid, I was happy. That mode is more efficient than a pure series design, by indirectly coupling the ice into the system they can get 10-15% more efficiency by directly using the energy for propulsion. As USBseawolf loves to say, if you have it why not use it.

A 30kW microturbine, the smallest that could reasonably support long-range driving is not as small or efficient as you think. Take for example the best selling microturbines from Capstone. The small diesel Capstone "30kw"unit produces 29kw but is 30in x 60in x 70in and only 25% efficient. So from 1 gallon it would produce 37.93 * .25 = 9.4875 kWh of power. Given the Volts EPA EV rating is 360w/mile that would provide for 26.35 miles per gallon of diesel. Even at iMEV at 290wh/mile would only get 32 MPG with that. Can you imagine the uproar if that was the HWY CS MPG? If you want an effective microturbine, you'll have to double the efficiency from what is on the market

Of course that model is not designed for a vehichle, and with some tweeking one can reduce it to within 10% of the size of the ICE engine in the volt (but it would be ~200lb lighter). One can push some efficiency using water cooling, messing with the conversion voltages and such so that with enough effort get it up maybe mid 30s mpg for a volt sized (maybe 40 for an iMev). Can do a little better if one gives up on liquid fuel and goes gas (bump generator to 30% or more efficiency), but propane or CNG fueling would not be viable for more people.

Could always go with a Range Extender behing an EV Which at least only gets used when you need the added range. Here is 30kw extender:




At first I wished the Volt team had gone with an Atkinson cycle, and maybe a larger engine, both of which should allow more efficiency though since we've not seen the BSFC for sure, its hard to tell how well the engine is being controlled. But after looking at I realized they probably made a good choice, since for most users, the ICE is used so infrequently, it then becomes a balance of fuel efficiency vs cost efficiency. In my 6400 miles so far, including many long trips (trips >100m), if the Volt had had a 50mpg engine vs the 40mpg I get on the highway I would have saved at best 20% of my fuel, or about 7 gallons of gas. The car is expensive as it is, so using off-the-shelf parts already being produced/maintained, was a reasonable engineering choice.

With respect to the clutches.. they are not physically that big, nor that complex. Its nothing compared to say an automatic transmission. The Volt will speed-match components before engaging/disengaging them so there is little stress in the process.

 

The graph says its uses the 11mile EPA estimate for EV. You only should subtract 11 miles not 15. I will admit it is is slightly off because 11 is EPA blended battery usage range but presumed 0 gas in that 11 miles but that eror is in the PiPs favor and in reality is nothing compared to the actual variations from drivers and conditions.

 

Two important points keep obscuring this discussion:

1. We do not buy electrons. We buy electric power, which is delivered as alternating current at a specific voltage. The electrons move back and forth along the wires, creating a sort of electrical pressure wave. No given electron moves very far, so no single electron ever travels from the power plant to your house. The power on the grid is the sum total of these pressure waves in any local segment of the grid, plus or minus whatever flows into or out of the local segment.

2. What we are all concerned about is the impact of our lifestyle on the environment. This impact is related to our use of energy vs the energy that we generate or cause to be generated. It is just as "green" (in terms of our net impact on the environment) to install a wind generator (or pay for one to be installed) in another state and buy our own power from the grid, as it is to install a wind generator in our own yard and live off the grid, assuming the same amount of energy generated and used in both cases.

Electric power is fungible because one unit is indistinguishable from another. What one producer charges, compared to another, is irrelevant. A dollar spends exactly the same, whether it cost me one minute of labor or twenty minutes of labor. Once it's in my bank account it is indistinguishable from all the other dollars in my account.

Assuming the electric utility is honest in its accounting, someone who pays for "green" electricity is assured that for every kWh s/he uses, one kWh will be generated from green sources, and his/her electric usage is "green." (Of course, even "green" energy use has environmental impacts, but those are far more benign than, say, coal.) It is not valid to charge someone with coal usage if they have chosen to buy wind power, because no more coal was burned to supply their power demand than if they had used no electricity at all.

This is why a grid-tied PV system is just as green as a grid-independent PV system. And it can be more green, since in the latter case, some of the potential might not get used. And a grid-tied system enables peak shaving, whereas an independent system does not.

 

That's an interesting history of the Volt's development that you have conjured up there.....

There was no custom engine. The original concept design simply used the already existing 3 cylinder variant (Z10XEP) of the same "GM Family 0" engine series as the 4 cylinder engine they are currently using.

I believe the engine choice was disclosed in 2008. I haven't researched the reasons for the change but they could have wanted a little more power output or perhaps there were noise or vibration considerations. Or, maybe it was cheaper to share the same base engine as the Cruze for manufacturing efficiency reasons. Also, we don't actually know the efficiency tradeoffs involved. Usually a smaller engine is thought of as more efficient generally but the Prius switched from 1.5L to 1.8L in gen 3 and improved efficiency.

As far as anyone knows, the Volt started off with Lutz as an idea to do another all-electric car but was quickly switched to a EREV concept for all the reasons that make PHEVs more practical for many people today. However, the idea was apparently always to have a full power EV experience with an emphasis on usable battery range with gasoline backup. As I've written before, this results in different engineering tradeoffs than a smaller battery pack that inherently cannot support full EV power and needs a blended design.

GM said the 2007 concept car was a serial hybrid and insinuated and implied that this remained true until Sept. 2010. However, the possibility of the current design was being developed at least as soon as the car was approved for production in the latter half of 2007. The patent describing the Volt transmission was filed in September 2007.

Why did they continue to describe the Volt as a serial hybrid? They have said it was related to intellectual property disclosure concerns but they also may have been concerned about implementation risk since this was a new transmission design even though the hardware derived 75% of its parts from the FWD version of an existing 2-mode design as well as major parts of its computer firmware . They may just have wanted to retain the ability to fall-back on a simpler serial design in case of unexpected problems.

 

Then let me restate this for you. Everyone but the fan bois knew that the volt was going to sell to initial adopters that liked PHEV technologies.

John why would you focus on some of those sites instead of the facts since you are one of those that "already knew".

Blogs are all about distorting reality. I actually read the news articles. You seem to be selecting things to make them look distorted. Why not just judge the cars for what they are, instead of hating one because of some fan sites that you were trolling?

Here is the oldest thing I could find from PC, and you are on it. Seems gm over estimated before bankrupcy, but numbers are for initial adopters, price was about dead on, delivery was on time
http://priuschat.com/forums/prius-h...ild-tens-thousands-chevy-volt-plug-ins-2.html

 

Thanks for the historical spelunking. I particularly like the comments that there would 100's of thousands of Plug In Prius by 2011, when they just rolled out in 2012 and will only have 12K this year.

Multiple comments in that thready about "just do it". Been there. Done that. GM built more than 10000 volts in 2011 not too far from projections from 2008.

In John's defense in that thread he did say they " start building lots of affordable, clean, and efficient hybrids."


Well in my view they they did. Its not an inexpensive hybrid, just affordable (unlike Tesla Model S with the range I need).

 

Ok, then help me explain this. I've calculated US consumption to EU units:
Volt: 37mpg = 6.35l/100km
PiP: 50mpg = 4.7l/100km

PiP does 21km on electricity, Volt does 56km on electricity. I've plotted this graph:
(4.7/100)*x= (6.35/100)*x - 2.12 - Wolfram|Alpha

Blue line represents PiP consumption after it switched to ICE. Red line represents Volt. It turns on the ICE 56km-21km = 35km later than the PiP, which is shown by red line crossing the X axis.
Both lines meet at 128 kilometers. When you add the 21km, which were subtracted at the beginning, then the overall number is 149km = 93 miles.

Where's the error in my calculation?