I've thought about this at times. How do you actually come up with mileage? My sugestion is to have two numbers. The first gives the range on electric only, the second is the mileage you get when it goes into standard hybrid mode.

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This is absolutely not true when Nanosafe 2nd generation from Altairnano (or tor the matter Electro Energy bipolar wafer version soon to be available)is used.
NanosaferEv.com

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Why would you not plug in your series hybrid? The miles you travel on electricity are about 10 times cheaper than the ones you travel on gasoline. And plugging in at home in your own garage is much more pleasant than visiting a gas station.

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These are certainly questions that need to be answered. How to calulate MPG for plug ins is already a big questions for those conversion kit companies. Of course they claim the biggest MPG number they can based on EV driving only (and even with those numbers, you'll still never get your $10-25K back).
However, for EPA ratings, the gov't will decide how it's done, not the car companies. I'd say keep the tests as they are for hybrids (which requires the battery to be at the same state of charge at the beginning and end of test), and add a "Miles on EV only" number to it to show how far you can get by plugging it in. Otherwise, it gets way too messy.

On a separate note, the title of this article makes no sense, and it is contradicted by the blogger in the article itself :
"I think the first plug-in hybrids will just be better hybrids and get better mileage than traditional hybrids only because they have larger batteries."
I agree with that statement. Some people have added extra batteries to Priuses, and those cars do get higher MPGs (even if you don't plug them in). By the way, a Prius battery only weighs about 100lbs, so doubling the capacity really doesn't add much weight.

Please change your title to reflect what is actually said in the article, since
a) you have no proof that MPG numbers for PHEVs will be lower,
b) that title is totally invalid anyway since nobody knows how MPGs will be calculated,
c) the small amount of evidence so far points the other way, and
d) you contradict yourself in the article

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Perhaps we should ask what the gas mileage is if you don't put fuel in it. Then again, perhaps this is a silly question. Any mileage figure is rife with caveats; this just seems like another one. Just define a standard "profile", just as the EPA currently does today.

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I don't understand what this article is trying to get out. "Fully change the batteries from regenerative braking?" Well, maybe, if you're NEVER going to use the electric mode and you're planning on driving a very long time. Otherwise, there is no way that captured brake energy alone would contribute more than a tiny amount to the batteries.

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ABG really needs to get an editor to read articles before they are submitted, this one is high on rhetoric, light on facts and borderline incoherent. It reads like last nights bar conversation about hybrids.

The sensible way to record mileage is:
Battery range: 20 miles.
Fuel econ (battery neutral): 38mpg/42mpg.

It is absolutely pointless to get to get into the bullshit game of combining plug in energy and gas and calling it MPG. Plug in every 20 miles and MPG is infinite. Or dream up any plug in interval to match up with any MPG you want. This is a pointless exercise in bullshit. MPG has to be quoted in the battery neutral condition.

Anyway lame blog post, that is barely average quality for a forum posting.

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Traditional hybrids increase efficiency which just means that we burn less gas. They are a good first step in making the oil that we have last longer, but any fool can see that oil is limited and literally everything we have depends on it! We must rid ourselves of this addiction and embrace multiple and diverse renewable energy sources as society is in jeopardy.

Electrification is the only way to fully embrace energy diversification and plug-in hybrids are the next evolutionary step along the way to full vehicular electrification.

The problems with electrification include (1) generating costs/efficiency via renewable sources, (2) transmission losses and (3) lack of cheap and efficient storage methods. These are the things we need to work on and plug-In hybrids will go a long way to provide motivation to solve these problems and deliver us from oil.

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I think this is a non-issue.

We can do an analysis of existing data and find out what percentage of your total mileage the "average" driver will drive with batteries only, assuming some "reasonable" level of state of charge at the beginning of every day. The sticker should say something like: "35/40 MPG without battery assist, 60/70 MPG will 80% battery capacity."

Yes, it's taking "an average of an average of an average", but given all the wildly changing variables in the mix, you have no other choice, and it's only slightly more generalized than giving a city/highway pair of numbers for a plain old gasoline engine car now.

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I think the article is based on at least one misconception about how PHEVs can (and should) work. There is no reason to ever "charge up" the battery to a high state-of-charge using the engine generator. There's no reason to have any sort of button or control to tell the car to do this, it would be pointless.

I'm going to pull some numbers out of a hat here, for illustrative purposes. . .

Let's say you've plugged in your car overnight and start a trip with your battery at 95% state-of-charge (we'd never use 100% as it would damage the battery). You drive on electrical power for 40 miles or so, until the battery is depleted down to 10%. Then the genset fires up. . .

From this point forward, your PHEV is running in a mode similar to a conventional non-plug-in HEV. It's going to try and keep your battery somewhere between, for example, 10% and 20% state-of-charge. It only uses a small portion of the battery's capacity.

Why not charge up to 95% again? There's nothing to gain, since only a small fraction of that capacity is needed to run as a HEV. The generator is much less efficient than grid power, so it makes more sense to leave that extra capacity empty, ready to be filled from cheap grid power whenever the next opportunity arises.

The only catch -- and it's a minor one -- is that if you *never* plug in a PHEV and you run it in HEV mode all the time, it's going to be somewhat less efficient and less cost-effective than a true HEV. But not drastically so. And I think most people will easily get into the habit of plugging in when they have an opportunity, so I don't see this as a big problem.

As for the EPA. . . they've got a bit of a sticky problem.

The simplest approach would be to establish some kind of standard driving cycle for PHEVs so you can give buyers a single number for comparison. I can see a lot of pitfalls, though, and I can imagine car makers optimizing cars for the EPA rules rather than optimizing for their customers' actual needs. It would be forcing everything into a one-size-fits-all standard, and I'm afraid one size won't really fit all.

Slowhand may have a good idea. Give buyers a range in EV mode and a MPG estimate in HEV mode, and let them figure out which is more important to them. However. . . What happens when you've got a parallel PHEV that doesn't wait for the battery to run down before using the ICE?

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Why would a PHEV refuse to charge the battery with regnerative braking? Regenerative braking energy is "free" energy. It doesn't make sense to not use it just so you can plug it in and PAY to fill the battery.

Any car that adds more complexity adds weight and reduces efficiency. A hybrid isn't as efficient in steady-stage highway driving as an underpowered gas-only car (basically take the motors and batteries out of the hybrid).

The last question:
'As a consumer, what's the minimum miles per gallons increase would convince you to take the time to plug in a car?'

is completely meaningless. autobloggreen shouldn't be asking it.

You cannot measure the efficiency of a PHEV in "miles per gallon". If I drive it only 1 mile it uses zero gas, does that mean it's using no energy?

I guess they'll have to measure the efficiency in Joules/mi, or "miles per gas gallon equivalent energy".

Efficiency aside, I will pay extra for a PHEV if I can drive my regular circuit to work and back without putting gas in my car. That means about 25miles per day I think.

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What would you put on a sticker ?
Ideally, something as close to truth as possible. You would say, this is an electric vehicle with 40-mile range, i.e. no gallons involved.
Exceeding that range, you get X miles per gallon, should you ever want to use this feature of the vehicle.

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I think we're missing a more important point here. MPG is irrelevant in an electric, PHEV, or any other alternative fuel vehicle. The only reason we have historically used MPG is because virtually all cars used gasoline. It made sense in that context, but not any more. Even comparing MPG for different liquid fuels, like gas, ethanol, and diesel, is misleading because they have different energy densities and cost per gallon. I suggest the more appropriate measure is MP$. How many miles can you go on a dollars worth of fuel, regardless of what your fuel is? That is a much more meaningful measure, and it will better illustrate the relative advantages of different fuels.

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"Battery range? EV mode? Who says they will have an EV mode!"

I do. I'm not buying it if I cannot do my commute on full EV mode, and I suspect I'm not alone. Is there any market research on the expectations of people who plan for their next car to be plug in? This isn't academic for me -- because I'm not replacing my ten year old car until I can buy a plug in car.

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"I suggest the more appropriate measure is MP$"

Its a beatiful measure, but this one is even harder to quantify than the equivalent-MPG trying to be forced here, because its dependant on even more variables. In addition to driving locations, distances and style, you have variability on fuel prices, price of electricity you charge from, frequency of charge and average range driven and whatnot.

You can measure and give "Cheapest MP$ awards" for people for hundred thousand miles driven in particular type of vehicle, but its not a number that describes the vehicle itself. It describes its user.

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