Volt 2.0: Ruess "It will leap-frog... the competition"

This in a nutshell is the GM Volt and it's marketing: Efficiency does not matter, electricity consumption does not matter. Only MPG(petrol) matters.

To be fair, most of the people I see post on Volt forums accept this premise so GM is singing to it's choir. It is no different that GM only publishing stats of how big an engine Corvette owners choose.

People in this forum tend to also evaluate a car based on efficiency and carbon emissions and in that regard the Volt fleet stats are pathetic.
1 gallon petrol + 22 kWh electricity from the grid is about equivalent to
1 + ((22*3*1.15)/34) = 3.23* gallons of carbon equivalent petrol, or 31 MPG(carbon)

*I assume 33% grid efficiency, 15% wall to car inefficiency (~ 13% losses)

 

Sorry, I thought it was second nature to those of us who discuss these questions ...

Assumptions:
33% Grid efficiency
13% wall to car losses
34 kWh/gallon energy

So,
22 kWh used over 100 miles is 22*1.15 = 25.3 kWh from the wall
Source energy is 25.3/0.33 = 76.66666667 kWh
Since a gallon of petrol is 34 kWh, source energy in gallons is 76.6/34 = 2.25 gallons
This is the electricity portion

because they do not want to use petrol. That is life living in the limited battery size world.

Really though, this is not a black and white world. I would have been more accurate had I said that the first priority of Volt owners is MPG(petrol)

Average emissions is a crock.

It is also tangential, and an issue I have mixed up in these posts. The discussion was energy efficiency per mile. Carbon per mile is a separate discussion, affected by efficiency but also by source energies. There the Volt also is poor.

 

You may be using 'rough' different than me ...

I approximate to within 5% (I think) the following:
emissions
coal 1x
NG 0.47x

Grid Source Mix
coal 4
NG 3
Clean 3

Carbon Mix
(4+3*0.47)/10 = 0.54x

---
Using NG as an assumption of marginal emissions at night is a poor assumption for most of the country. It *might* be true for CA, but my memory is vague on that point.

Because your marginal emissions are always fossil fueled, until clean energy is available in excess on the grid.

Please correct me if I am wrong, that the data is from 'on-star- which comes from the car. How would the car know wall to car charging losses ?

Second, the 33% efficiency is not from gasoline, it is from EIA data of national average fossil fueled power plant efficiency. I cannot remember if transmission losses from plant to home are included.

 

I've never seen anything that says OnStar data reports charging loss.

As for my data, I was quite generous by using 3.0 kWh as a "full" (from 23.5% to 85%) recharge. Realistically, I could use 2.75 kWh, sinc e that is the average ChargePoint reports.

In other words, PiP is even more efficient with it's electrical system than the recent posts reflect.

 

I can accept one of two answers:

• 1. Too variable to average; a regional fleet and TOU must be specified.
• 2. Somewhere between NG and Coal intensity. I tend to use 0.5 coal and 0.5 NG for marginal emissions because that approximates the national grid. That works out to (1x + 0.47x)/2 = 0.735x of coal. This works out to be some 50% higher upstream emissions that EPA is calculating based on national grid emissions or you are calculating based on NG alone. This carbon intensity is, I think, within about 15% that of petrol and on the national grid about 33% efficient from plant to wall.

CA may be different, but the coal sourced imports tend to get lost in the stats.

Fair enough, so long as GM is using those numbers in it's reports.

I answered your other comment already -- efficiency of renewables is irrelevant because all marginal emissions are fossil fuel sourced (on a regional level, for the next couple of decades at least, anyway.)

 

Because such a car would be giving up interior space and fuel economy. The Prius has established itself as the best hybrid on the market by a wide margin. No other hybrid can claim the same combination of fuel economy, interior space, ride comfort and reliability in one package.

 

This EIA link is a good place to calculate national source energy efficiencies.

 

The data on onstar is consistent with charging loss, but again, I don't know if it is a measured or a calculated figure. The amount is too high to simply be amount in the battery. If I use your lower figure for electricity, your mpge doesn't change much, it goes up to 62.2 mpge still far short of the median of volt stat users, but a little more above the 60.5 mpge average of all volt drivers.

As mentioned earlier, it would be great if toyota provided the statistics that gm is, but all we can do is guess. As a second source is there a prius phv site like volts stats that gives a large number of prius phv drivers?

I am glad that you are happy with your car, and that you are doing even better with it than you thought you would when you bought it. I hope toyota takes what they have learned from drivers like you, and the volt and leaf stats and gives us a much improved next generation that they roll out nationally.

Different people are keyed into different numbers. For a phev, the i3 + rex seems like the most efficient. We don't have years of data yet though. Obviously a the average volt will use less gas but more electricity than the average prius phv. There are differences of opinion on how to convert and balance the two figures. The epa gge is just one choice for a measure.

 

Huh? Where did that come from? PHV is darn near dead on with what I estimated.

The "thought" part is Volt being revealed as guzzler in the EV world.

I knew GM was putting heavy emphasis on avoiding gas usage under pretty much all circumstances. Achieving that required tradeoffs. But since the market & politics was in the mindset of electricity=good, there would be no incentive to make it use less. After all, there was a great deal of "40 mile" promotion and the pack was supposedly big enough to easy handle that.

 

Tesla Model S is more of an electricity guzzler than the Volt.
Although if you want the true guzzler, take a look at the Fisker Karma. It was somewhere around 63kWh/100 miles.

 

Was it karma that Fisker went bankrupt?

 

FYI, Voltstats has 10% of all the Volt miles.

Using it is very skewed.

Hey use PiP top 20 MPGe stats.

95 vs 98 MPGe.

Model S is a 7 seater full size car. Volt is a 4 seater compact.

In that perspective with performance, Volt is an electricity guzzler/grounder.

Dup.

 

Oh voltstats has a much lower percent than that, its less than 4% of the miles, those are non-anonymous. That is why I gave you the on-star breakdown, which is quite different. We don't have the standard deviation but we see self selected people on things like fuelly and voltstats are theorized to be skewed, and with the on-star data we can see how much. voltstats drivers had higher percentage of electric miles just as you would guess. Now the funny thing on this thread is I am being both accused of being volt biased, and of selecting a data set that makes it look bad.

The difference between volts stat median and volt fleet average mpge was approximately 9 mpge, but volts stats mean was around the same as the whole fleet. The difference on electrical percent was 16% (79% versus 63%) the volts stats mean was 72% still much higher than the fleet. The reason the mpge is close is volts stat skewed charge sustain mpg lower. More gasoline miles (long gasoline trips) seemed to result in better mileage. Volts stats median charge sustain mpg is only 34.2 mpg and some outliers appear in the data.

OF course you and john represent a much smaller sample size of prius phv miles. If you can get 4% of prius phv stats together or even 1% it would be appropriate to compare that to the skewed volt data set. I'd love to see toyota collect and give us the stats. I honestly don't know if you and john are average or high or low outliers without more data, but I do know 2 or 20 is not enough data points. Volts stats has 37 million miles of data, on-star over 1 billion miles. I like big data

My local utility is part of a federal program to monitor charging habits (including marginal generation and home versus public charger). Unfortunately toyota has chosen not to participate. I'll report the figures when I have them.

You said

I thought your posts reflected your thoughts, and now you found it even more efficient. I don't quite know what to make of it now. Am I wrong about you being happy about your car too. I mean I did read that in too, but could be wrong.

I don't quite get guzzler of the ev world. We get the volts stat median of 69.5mpge, and the on-star mean of 60.5 mpge. You got or guestimated 62.2 mpge. I find that your prius phv did 10% worse than 50th percentile of volts stat drivers, but the bottom rung lowered the average bellow you so you were 3% better than the fleet average. Even the bottom wrung which rarely plugs the car in, would not be considered a guzzler, although it does consume more than a prius, less than a Camry or iq or corolla. Perhaps you could use a different term than guzzler, and I might understand.

The advantage to better electrical efficiency is a smaller battery (less volume, less weight, lower cost to manufacture - possibly one or all). As gm has worked with the volt they have made it more efficient which has stretched the electric miles for the new 2015 (gm has not retested with the better 2015 battery but 2014 with less usable SOC was 98 mpge and 38 mile range versus original 95 mpge and 35 mile range.

Compare Side-by-Side

Of the non-exotics the mercedes B class bev is the worst with 84 mpge, the bmw + rex (seems more fair to add the ice weight) is best at 117 mpge. The prius phv can not be compared directly as it must use gas to do the test. It is at 95 mpge.

This is where personal opinion of electricity versus gas comes into play. We must use some gge figure to compare the prius. If we use 33.7kwh/gge then the prius falls slightly worse than the volt in epa testing and falls further in guestimated median vehicle. At 30 kwh/gge the prius phv is identical in epa testing (real world we don't have the prius data). Since the average is mile weighted, and the less efficient cars are older and likely traveled more miles, the volt average fleet data is biased toward the older cars.

I would not expect the next gen volt to have the dramatic weight savings to greatly improve its 98 mpge rating, but I expect more usable SOC, which will raise the mpge of electricity gasoline mix, and the charge sustain mpg definitely has room to improve.

 

I do a lot of long-distance driving. That's what happens when you date, get engaged, and do lots of stuff with her far away family. I take setback several trips per year up north with bikes on back too.

So, I could be on the low end, depending on what's considered typical for commute distance.