calculation details of Volt's 230mpg city estimate

Well that sounds reasonable to me. 48mpg in CS mode is what I would like to see as well. Of course some are pegging it at 38, others are speculating that the Volt will surprise us with HCCI and CS mpg over 50. I am looking forward to finding out the real world specs.

 

Of course, we are also talking about a $10,000 premium or so for the Volt.
So hopefully they can do much better than the 40 mile EV range, or 48mpg CS mode fuel efficiency.
GM could also help with more information. The ONLY thing we have to go with is the fact that over the 43(?) mile epa track the volt gets 230mpg.
43/230 = .187 gallons.
If the ev range is 40, the Volt used .187 gallons over 3 miles, giving you about 16 mpg??
My numbers must be off somewhere. Perhaps the test track is more than 43 miles?
Non-the-less, more information will be helpful.

 

Don't get your hope too high. From what I've read, HCCI efficiency is only as good as Atkinson cycle ICE. Volt won't have direct mechanical path to the wheel so it will always be at disadvantage.

 

All the U.S. "big three" automakers own huge chunks of stock in oil companies, and the oil companies own correspondingly huge chunks of stock in auto makers. The oil companies and the big three car companies have overlapping boards of directors. Thus GM profits (indirectly through its stock interests) in oil, and the board members are not going to take off their oil company hats when they're sitting in the GM board room.

Wrong. The Prius engine can send power directly to the wheels when that is most efficient. The Volt's power ALWAYS has to pass through the generator-motor chain, losing energy in the conversions. And in CS mode, the battery is indeed dead weight unless you have long downhills where a significant amount of energy can be recaptured. It also remains to be seen if the Volt's engine will be as efficient as the Prius's engine.

GM now says that the gas engine will not recharge the battery in CS mode. This means that the gas engine must be powerful enough to provide acceleration in CS mode. This is one of the principal reasons why conventional cars are so inefficient: The engine must be big enough to provide the power that is need for brief periods. Since the Prius nearly always has reserve battery power, because it recharges the battery when needed, it can always draw on the battery for energy for the electric motor.

Without the ability to recharge the battery, the Volt will either need a bigger engine, or will suffer from poor performance in CS mode, because the depleted battery will have nothing to offer. It will indeed be dead weight once it is depleted. UNLESS it reserves power in the battery, switching to CS mode before the battery is depleted, in which case the EV range will be that much less, and the ICE will run more. And for longer trips it will still deplete the battery and have poor performance if the ICE is small, or have poor FE if the engine is big.

HSD is simply a much more efficient way to burn gasoline, and pure EV is a more efficient way to run on electricity.

"What if" is not an argument. What if pigs could fly? Then we wouldn't need cars at all. We could just ride pigs everywhere. When asked what mpg the Volt will get, GM says 230. Why don't you just do your calculations with that? The Volt will get 230 mpg and the Prius only gets 50. That means that on a drive from L.A. to N.Y.C. a Prius will burn 56 gallons of gas and the Volt will only burn 12 gallons, a savings of over $100 for the Volt. Or in a 15,000-mile year, the Volt will use 65 gallons and the Prius 300. Or $162 vs $750. Of course, if you believe that, I'd like to sell you the Brooklyn bridge.

 

No. You are wrong.
The Volt has an undersized engine like the Prius, can re-capture braking like the Prius and finally has an engine optimized for a narrow set of operating ranges. The battery is not dead weight.

It is true that it remains to be seen if the Volt's engine will be as efficient as the Prius's. It could be MORE efficient, it could be less. We will have to wait and see.

Much is made of the mechanical vs electrical routes of energy transfer yet there is nothing that says that the Volts electronics will not be more efficient then the Prius's. While I love the Prius PSD, it also has looses associated with it. The idea of a serial hybrid is a sound one and so far there seems to be nothing wrong with Chevrolet's implementation.

 

I think CS will fall between 30 and 37 mpg, with my guess at 34, based on range data GM likes to use and the reported 8 gal fuel capacity. But maybe it will get 50 mpg, who knows. Either way, I'm not a buyer. At 34 it is a yawner. At 50 I have to save up to buy a pig from daniel, with the xebra paint scheme.

 

"So far" there "seems" to be nothing wrong with GM's implementation because SO FAR no independent tester has had a chance to try out a Volt. So far, the Volt is a pig in a poke.

I do not sell pigs or Xebras. If pigs could fly I'd want one, just as if the Volt got 230 mpg I'd want one. And I promote the Xebra because it's a fun little car and fits my needs pretty well, until I get my hands on a Nissan Leaf.

 

Drat. Foiled again.

Oh wait, this isn't just three words thread is it.

 

So GM and Chrysler weren't forced to sell their stock holdings to satisfy their debts when they went through bankruptcy?

 

So are you saying that after the battery is depleted and the Volt is running on the ICE, that regen braking will recharge the battery and the car will revert to EV mode for a while until the battery is depleted again?

 

That's a point I had not considered. I do not know if they were forced to sell their holdings. However, interlocking boards of directors means that the people actually running the company have oil interests at heart.

Imagine you are on the board of directors of two companies: How likely are you to implement policies at one company that will hurt the other?

In spite of the perverted court ruling that says that corporations are "persons," a company is not a person, with its own interests; a company is run by people, and the interest of those people are seldom the same as the interests of the stockholders, and even less often the same as the interests of the nation. When criminals run a company, they use it for their own benefit.

 

Wait a second there. Increasing engine size alone does not increase efficiency. It helped on the highway mpg of the Prius because the 1.5l engine was in a bad part of its power band on at highway speeds. Toyota also wanted to give the car more power to make it more competitive.

If Toyota had re-geared the 2010 Prius and stuck with the 1.4 they could have gotten better mpg in both the city and highway. They lost mpg in the city by going up a size.

 

No, but I am saying when you brake you are putting power back into the pack. This increases city mpg a good deal and very slightly on the highway. Who knows (or even who cares) if you put the Volt on the top of a mountain if it would re-charge the battery on the way down. That is not going to be a common occurrence.

 

As I've said before, we've seen with the Prius that re-gen braking recovers only a small amount of energy. Therefore its effect will be small in the city and nil on the highway. It can be significant in very hilly terrain, compared to using friction brakes.

What small benefit re-gen braking has, will be seen as:

1. An increase in range while in EV mode; and
2. When used in CS mode, a reduction in energy used to re-charge the battery when you plug it in; and
3. An improvement in longevity of the brake pads (unless GM compensates by using inferior brake pads, which would not surprise me, given GM's greed-based behavior historically.)

If the car will not go back to EV mode once in CS mode, then re-gen braking will have no effect on mpg in CS mode: All it will do is you'll be bringing the car back to the charging port with a higher state of charge.

 

As I have read all of the above interesting and informative post, a thought occurs to me that I do not recall anyone mentioning.

Inasmuch as the Volt's ICE is not connected to the drive wheels (not speed dependent), and only to the generator, might a situation occur where the battery is [near] depletion, it is dark, the lights are on, the A/C is running, and the ICE starts to charge the battery. I have read that it will run at various rpm's depending on the electrical charge required. Might the situation occur where in stop and go traffic, the ICE is "racing" at 3000-4000 rpms while the vehicle is stopped in traffic? Under those conditions, I love the way the Prius ICE shut's down and is quiet.

Just curious.

 

Households that cannot afford two cars, commute less than 30 miles a day, and are willing to spend $40,000 in order to save $625 a year on gas.

Or people who want to drive an "electric" car, but are so worried about running out of juice that they will prefer a 30-mile range plus a gasoline engine rather than buy a Nissan Leaf with a 100-mile range.

 

DING DING DING, We have a winner! The general public are idiots. hence the need for gas empty light and all the other "idiot" gauges. Do you know how many people run out of gas everyday? How people ignore the gas empty light and continue to drive?

You have people here on Prius chat that run a Prius out of gas! if a person were to run out of power in an EV it would severely damage the battery. I have personally never run out of gas.

If nissan has it's dream of AAA having a booster truck, it would either be a quick boost followed by a long recharge at a charging station ( I would think a quick charge would not be recommended from depletion) or a long charge right there. So that's atleast a 30-45 minute wait for the recharge and if it happens repeatedly it compromises the range. so that 100 mile range will turn into a 50 mile range.

Or that the volt can serve the role of two cars (the jack of all trades, is the king of none). So that a person can still have an ev commuter car and have a car for extended trips. The general public has range anxiety and it is mentioned in EVERY article about an ev (check tesla reviews to start). So if some of the general didn't have that fear, the media is doing a hell of a job creating one