PiP/Volt January 7-11 Switcheroo

It just dawn on me that I have been using fuel efficiency and vehicle efficiency interchangeably. They are not.

Volt can be more vehicle efficient yet PiP can be more fuel efficient. The way the two can be differentiated is to include fuel production for fuel efficiency. Vehicle efficiency is simply EPA measurement, MPGe for electricity and MPG for gas from the plug/pump, ignoring the fuel production in upstream.

We know electricity is more efficient at vehicle efficiency level. So, the more electricity a PHEV can use, the higher composite MPGe is going to be. That's the edge that Volt has over PiP. However, if you breakdown the electric mile and gas mile and compare the efficiency of both fuels, PiP will win in both.

Fuel production for gasoline is about twice more efficient than electricity. For that reason 100 MPGe on electricity is roughly the same as 50 MPG on gas. Emission data shows this -- 99 MPGe Leaf is about as clean as 50 MPG Prius.

So, if you take account of fuel production, PiP wins. Per EPA, the emission of tailpipe and beyond (upstream) for PiP is 210 g/mi and Volt is 260 g/mi, using average electricity and gasoline mix.

The point of this post is not to brag about PiP or bash the Volt. I am simply using these two plugins to explain different levels of viewing efficiency. Vehicle Efficiency is a partial view (tank->wheels) and Fuel Efficiency is a complete view (well->tank->wheels).

 

I was wondering how long it would take usbseawolf2000 to throw in the towel and fall back on his ghg argument.

 

Actually, the opposite. I am enjoying these calculations and what they are revealing. I know Jeff's final day number may change the numbers. I just did them anyway to satisfy my curiosity.

 

This is a constructive discussion so nobody need to throw in the towel.

What is the breakdown of your electric mile efficiency (MPGe) and gas mile efficiency (MPG)? From your signature, I know the composite is 83.3 MPGe.

 

Ah back to the GHG argument. The thing is, people don't live in "average US". We live specifically where we are. The swappers in this test, and I, live in the SF bay area. Here, PG&E says .524 lb Co2/kwhr, and it's getting cleaner as the years go by. This is about 71 grams/mile on EV, at the ~30 kwh/100 miles I get.

Yes, I don't have a fifth seat. I've never needed it. My previous car had a fifth seat, I used it like once in 12 years. That one time, I'm sure I could have taken one of the other passenger's cars instead. How often do you go out in groups of exactly five people? Once you go to six, another car is needed anyway and you split 3+3 or whatever.

And that requirement for premium gas is a real killer -- at the ~25 gallons per year I'm using, that's a whole $5 ZOMG.

usb wants to declare the PiP more efficient for all people under all circumstances for whatever strange reason. This is a silly, strange exercise doomed to failure. It depends on the individual driver's commute & overall driving habits, where he lives, and by which exact metric you wish to do the comparison. Use some common sense. Which car is preferred depends on individual preferences and circumstances.

 

This thread is refreshing in that you have two openminded people actually swapping cars and making intelligent comparisons using real life experience. It is limited by their driving distances so is only generalizable to similar situations but the narratives have been fun to read and are informative. The bottom line- both vehicles are engineering advances and are two of the best cars on the planet for efficiency. I applaud the VOLT for finally getting an american car in the game. The real test will come when all incentives are gone--will it be able to compete? Who will develop the first non-government subsidized/incentivized car that will show a economic payoff. There are some green motivated people. But to the masses, they want real savings--ROI. If they can solve the battery cost issue we will be off to the races with excellent economic and environmental consequences.

 

when you exit comparing the vehicles and move to externals, that is throwing in the towel

the detail is at fuelly except for knowing the EV miles which would be 8912 @ 1/1/2013

$1.67/100 miles is ultimately my measure of efficiency. YMMV.

 

I was parked next to a Volt last night at a ChargePoint port, using L2 my PIP was drawing 2.270 kW, the Volt was drawing 3.038 kW

Cacti

 

That would be 33% faster but I also think you may have caught the Volt near the end of a charge session. I normally see 3.3KW when charging my Volt, except for the last few minutes. I haven't seen a PiP yet.

I have also seen less than 3.3KW at a station that was intentionally limited to 2KW. I don't go to that station anymore. The manager said it was intentionally limited because it shared a circuit with the public swimming pool's water pumps.

 

The Volt had only been charging for approximately 10-minutes. I had noted the 3.038 kW on a previous time too at this same location when there was a Volt (I think it's the same vehicle?) charging. The last few minutes for the PIP is approxmatley .640 kW.

Cacti

 

Interesting. The line voltage must have been at the low end of the range. I think the onboard charger is limited by Amperage so low Voltage would result in a lower KW.

I have seen some graphs of PiP charging and it does have a rather long tail, especially in warm weather.

I wonder if the station was connected to a parking lot light circuit. Those are typically at 208V (3 phases). Maybe not since the PiP would probably be drawing less than 2.3KW as well.

 

Thanks to Jeff and David for sharing their experiences. It is very informative!

 

Well welcome to the next stage of enlightenment.

To advance further you must overcome your next levels of mental blocks including four problems in your current analysis:
1) you are using only partial upstream (well->wheels) as opposed to full lifecycle costs.
2) you are thinking about efficiency of electricity from coal, not from renewables or nukes
3) you are using averages that are irrelevant (consider what you buy, not what others buy)
4) you are weighting GHG as the only item, ignoring economics, security and other dimensions of the choice.

You and I have had many exchanges on this.. so I'll just point you back to this post
Toyota November Tops US Electric Plug In Vehicle Sales For November | Page 12 | PriusChat where I presented numbers to show that if you include discovery of oil (a proper part of upstream analysis) and the renewables/nukes, the GHG favors more electricity use. Using vehicle efficency, which is what we purchase, makes sense. Using wells-to-wheels which is a partial upstream but ignoring the full upstream, makes much less sense (either do full LSA or don't go upstream).

And again, as stephent stated above, no one buys the national grid, consider your source of energy and what one buys. The individuals usage pattern is what matters. If one has a short commute and lots of long trips the PiP can be better but for those with more than 12miles and under 100 a day a bigger battery can be more efficient. And if you care about GHG, then one can choose to buy renewables and a bigger battery. If you care more about national energy independence, you can buy a bigger battery and US-produced energy.

 

To JeffN and /Dev, Thanks for the experiment and your reports. I cannot say I was surprised by the overall outcome, but it was good to see empirical data and personal impressions from real users. I was most surprised to see the difference in driving styles and trip profiles made. I somewhat expected /dev to be at 40+ miles per charge in the Volt, but I then again I know speed kills range.

 

So the breakdown for Volt is about 128 MPGe on electric miles and 46.49 MPG on gas miles.

With PiP you also got about 128 MPGe on electric miles and 65 MPG on gas miles.

The composite of the two numbers depends on the ratio of both fuels. In your case, Volt has higher EV ratio so your MPGe composite is higher. Looking at the breakdown, PiP is more efficient.

 

Average US electricity mix means, if there are equal number of plugins in every state, the emission will be such amount. The actual sales of plugins are not equal in every state and if we weight it according to the sales, PiP still come out cleaner (and a lot less hours charging).

You don't get it. It is not only about the seat. A midsize car cost about $3,000 more than a compact car. Midsize cars cost more to operate because compacts are more efficient (due to being smaller, lighter, etc).

In the case of midsize PiP, it costs less (to purchase) and more fuel efficient (look at the breakdown) than the 4 seater compact Volt.

That may be true for you but per GM (OnStar data), 39% of the miles (of all Volts) were driven on gasoline. So, no cherry picking.

You clearly misunderstood my position. You seem to have an open mind and level headed for a constructive discussion. I hope my above answers helps you understand my position more.

 

Electric miles: 8,912 miles
Electricity consumed: 2,850 kWh

Gas miles: 911 miles (9,823 - 8,912)
Gallons consumed: 39.25 gallons

Electricity vehicle efficiency: 105.38 MPGe
Gasoline vehicle efficiency: 23.21 MPG

You are doing better than EPA on the electric side by gas efficiency is just horrible. If you pay the electricity (22 cents/kWh) and gas ($3.7 gallon) the same as me, it would cost you $7.86/100 miles.

If you are afraid to go to emission discussion, we can stay at the efficiency.

Electricity well-to-wheel efficiency: 2,850 kWh / 0.39 = 7,308 kWh = 216.9 gallon(e) -> 41.1 MPGe
Gasoline well-to-wheel efficiency: 39.25 gallon / 0.85 = 46.18 gallon -> 19.7 MPG

Gas+Electric Composite well-to-wheel: 9,823 miles / 263.08 gallon(e) = 37.34 MPGe

Your 83.3 MPGe came crashing down to 37.34 MPGe if we include the fuel production losses.

 

1) A full life cycle comparison is out of my ability. I will not be able to find enough conclusive data to make a fair comparison. If you can, why don't you show the full life cycle comparison of the two?

KPMG survey just came out and automotive execs believe that EVs are no more efficient than the most efficient ICE, at the current grid mix.

2) I gave 42% electricity production efficiency (half of 85% for gas production) which I believed to be average efficiency from all sources (coal, natural gas, nuclear, renewable). You want to use the ideal case for electricity. I want to use the current grid mix.

3) Again, weight it by sales if you want.

4) I do consider the other dimensions. GHG is not the only item I discuss about. National security can be increased for both fuels by producing more domestically. Domestic oil production is projected to go up in two years (25 years high). Grids will become cleaner as well. So there are a lot of moving parts.