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SDG&E In-Use Study Quantifies Benefits of Two Converted PHEVs

A year-long study by San Diego Gas & Electric (SDG&E) studying two converted plug-in hybrid electric vehicles with 5 kWh Li-ion battery packs found that the converted PHEVs achieved a 60% increase in gas mileage, a 37% decrease in carbon dioxide (CO2) tailpipe emissions, and an 18% reduction in fuel costs compared to the same cars prior to conversion.

In response to increased interest in alternative-fueled vehicles, SDG&E evaluated the two standard hybrid vehicles for six months and, using the same pool of drivers, evaluated the converted plug-in hybrid vehicles for an additional six months.

Among the study’s results are:

  • The plug-in hybrid achieved 67 mpg, a 60% increase over the standard hybrid’s 42 mpg and a 205% increase in mpg compared with a standard car at 22 MPG;

  • The plug-in hybrid achieved a 37% reduction in CO2 tailpipe emissions when compared with a standard hybrid and a 67% reduction compared with a gasoline-powered car; and

  • The plug-in hybrid had a monthly fuel cost of $94, an 18% reduction from the fuel costs of a standard hybrid ($115) and a 57% reduction when compared with a gasoline-powered car with a monthly fuel cost of $219 at $3.85 per gallon.

Original equipment manufacturer plug-in hybrids are expected to be delivered to showroom floors across the nation in late 2010 and the efficiencies are expected to be higher than those demonstrated in SDG&E’s study, the utility said.



And can charge on renewable energy solar etc.
or off peak any.
onwards and upwards!

Kit P

Only in Southern California would someone claim that saving $11/month on energy with a 60 year payback period on POV with a 7 year life was saving money.

Of course “37% reduction in CO2 tailpipe emissions” ignores the natural gas burned in inefficient single cycle gas fired power plant.


The plug-in hybrid achieved 67 mpg, a 60% increase over the standard hybrid’s 42 mpg and a 205% increase in mpg compared with a standard car at 22 MPG;

Mentioning liquid fuel consumption for a PHEV without specifying the range of travel it was measured on, is absolute rubbish.

What if their PHEV car was electric-only capable, and was driven exclusively very short distances (ie lightweight car driven up to 15 miles) and recharged every time, without burning any fuel from tank, then the increase in mpg could have been MILLIONS % (they divide by zero, or the tiny amount of fuel that evaporated).

Like politicians wrote the report to impress masses.


If batteries are in short supply, then it is better to make more non PHEVs and spread the batteries around.

You really need to add a lot of battery to really put the kabash on oil. A 25KWHr battery would do the trick, not the 5 that they mentioned.

but again, if you have limited batteries, then it is better to make more Prius like cars than it is to make half or a fifth as many fully EV or serious PHEV.

But it is good that they are at least interested.

BTW - powering all of the autos in the US on electricty would require 10% of our present generating capacity (100GW). If everyone charged at night, I'm not sure we'd even notice. The output level of a power plant in standby mode at night is still a lot of excess capacity going to waste.


MG: Hit up Google's RechargeIT site for detailed information on their PHEV experiment.

All the data you could ever want and more.


The criticism on this site has been first class lately and as such it is incredibly valuable as reality check.
certainly makes me look and think harder and question my own views and prejudices.
Kit P this is for you.

This test fails to in any way describe the methodology for the CO2 emission figures.

Sure it doesn't mention how old and rusty the generator is,the test being conducted in California Could be nuclear, solar, etc? or a $50 Global brand portable generator so we cant draw any real world conclusion

But in Google world it certainly puts up a challenge.

Given the usual disclaimers for terrain, warm weather and test time span not including winter weathers etc and stated that the test conditions were set to show the PHEV at its best with fully charged batteries etc.

Kit P


You do not think the local utility doing the test can figure out where the extra electricity is coming from?

Doing an energy balance is very simple. The reason SDG&E does not provide more information is even the really slow would conclude that PHEV is not a good environmental choice.

Based on the data provided, SDG&E is being dishonest.


It doesn't really matter where the electricity comes from, what matters is the fuel consumption over the year (or in this case 6 months).
It is well below the 93.5 mpg that Google got, and that is a result in itself.
The point is, they did it, with cars that did not cost the earth (unlike fuel cells).
You can imagine that utilities LOVE phevs and so they should study them intensly.

Note that they are not that much better than normal Prii, and that the conventional car they us is downright awful.
If they had used a 30mpg ICE reference, it wouldn't look so rosy.

They do highlight how to measure the mpg of a PHEV - run several of them for a year and see what comes out.
The motoring magazines (and car companies) won't like it, but it really is the only way.
And it will vary hugely from user to user.


Utilities do love PHEVs and are positioning themselves now to control access to the grid. Precisely the reason to move away from "grid-lock" to new forms of independent energy generation. Utilities as presently implemented represent the same path that petroleum companies did a hundred years ago. Single point energy resources are a formula to repeat the past.

The time to overhaul the grid and its resources is today. Starts with de-centralizing single point generation in favor of distributed generation via RPUs. Large renewable resources like western solar/wind farms can service millions more consumers via DCHV if residential demand is offloaded to RPUs.

Still plenty of business opportunity for utils - but they'll have to give up heretofore cherished monopolies for real world competition from new, better technology. That's a good thing.

Kit P

Looked at the Google web site on PHEV. They are not using ISO 14000 methods of LCA to calculate ghg nor did they provide any rigorous economic data to calculate ROI,


Whether the SDG&E can tell where the electrical component was generated, I dont know.
They possibly source their supplies from a range of physical plant. This article certainly does not describe any model. I would have thought that the Google model with its slightly more detailed non model, one could work out fairly easily if there was any CO2 emissions from the electricity component.
I too would like an answer to that (ap)perplexing question.
The reasons I can accept, even agree with this presentation are to do with the forward looking possibilities where as you know any people wish to see low emission wind, solar wave etc too many to include sources being fast tracked for development against much resistance from the established view.
Surely we could see a range of Emissions from the electrical component from "near zero - to choking"
So where should the level be set?

I Agree that the omission of exploration or discussion of this matter is a real issue here. For those of us who now the bigger story, our view wont change much?
The average? god help us! consumer may well be misled.
Fortunately I dont come across too many of those , these days.

But that the report can represent the potential with PHEVS, Just as we seem resigned to accept the description zero emission BEV's ( I believe It's now called Z tailpipe emission vehicles. )

Henry Gibson

Put in 25 KWH ZEBRA batteries and you will get more fuel savings and 125 mile range. Cost savings are almost never done in prototypes or first production. ..HG..

Kit P


Of course every utility including SDG&E know where the electricity for their customers is physically coming from. I can go online to my local RTO and see if my utility is selling base load coal generated power @ $ 20/MWh or $50 /MWh. Since my utility is always selling, I am going to get cheaper rates than just a few miles down the road. I would benefit and my utility would benefit if I could get a PHEV at a reasonable cost.

For SDG&E, when off peak power is @ $ 15/MWh, the electricity is only coming from renewable energy or nukes. In this case, PHEV would not increase CO2 emissions by charging the batteries.

However, I would estimate that 95% the electricity to charge batteries in Southern California is either ugly or very ugly.

The reason SDG&E and Google does not calculate ghg from electricity is they know the answer would indicated that PHEV is just a form of green washing.


Wouldn't be surprised to see some of PG&E's new 900 MWh solar thermal energy get sold to San Diego. The present business model allows customers to purchase renewable electric service for a fee. For those who care, they can recharge EVs with zero CO2 emission. It'll just cost them more.

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