230 mpg

[Samm]

GM announced today the availability of the Chevy Volt claimed to achieve 230 mpg in city driving.

http://www.google.com/hostednews/canadianpress/article/ALeqM5j-WxUSxsW56eUU3UCKKGmbYvklvw


They did not say how many miles it gets per ton of coal...

[johnrocks]

What is both joyous and sad is the fact that a private company;after years of research made this possible; but government;having gave them billions;will be credited years from now for this marvel of capitalism,imho.

[RickRhetoric]

They did not say how many miles it gets per ton of coal...

:))

[EnchantedFrog]

Did they mention that it only goes 40 miles till it needs recharging?


Didn't think so.

[VCaddy05]

Did they mention that it only goes 40 miles till it needs recharging?


Didn't think so.

thats why it has an on board generator to charge you much further then 40 miles, hence the 230 miles

[Alaric]

thats why it has an on board generator to charge you much further then 40 miles, hence the 230 miles

You cannot run the onboard generator long enough on one gallon of gasoline to travel 190 miles.

I commute 17 miles to work. I could buy one of these and never put a drop of gas in the tank. So I would get infinite miles to the gallon.

Sam's point and Frogs point is completely on target - this thing still requires energy - so measurements such as mpg are completely irrelevant and meaningless for hybrid cars when applied as GM has chosen to use them. Don't suspend common sense in the headlong fall for the marketing hype.

[Chewbacca]

They did not say how many miles it gets per ton of coal...

But you could make a reasonable estimate.

The volt is publicized as requiring 25 kWh of electricity to travel 100 miles.
The thermal energy content of 1 ton of coal is given as 6150 kWh/ton.

Considering that power plants are able to harness between 40% - 60% of that energy, in the worst case scenario a ton of coal produces 0.4*6150 = 2460 kWh of usable energy.

Given the Volt's published energy consumption of 25 kWh / 100 miles the milage per ton of coal is 2460 kWh / (25 kWh/100 miles) = 9840 miles.

We can also do this with a gallon of gas...

1 gallon of gas contains roughly 36 kWh of energy.

36 kWh/Gallon * 0.4 (usable kWh/kWh) / (25 kWh / 100 miles) = 57.6 miles per gallon (of gas burned at a power plant).

I have no idea what the EPA's metric is based on. But it probably has to do with the fact that you can drive the car 40-50 miles without ever having to use the internal combustion generator (according to the DOT most american's, on average, don't commute more than 40 miles in a given day anyways). So while the car clearly uses energy (it has to come from somewhere), the consumer will on average fill up on a 230 mpg basis.

[EnchantedFrog]

This is what I found about the completely fraudulent method of computing mpg:

Mike Duoba from Argonne National Lab devised a method to determine the MPG of an EREV; first the car is driven from a full battery until it reaches charge-sustaining mode, then one more cycle is driven. If we use the highway schedule, the first 40 miles are electric. One more cycle is 11 more miles. If the Volt gets 50 MPG in charge sustaining mode, it will use .22 gallons of gas for that 11 miles. Thus 51 miles/.22 gallons = 231.8 MPG.

As becomes painfully apparent, the numbers are drawn from vapor.

[Alaric]

This is what I found about the completely fraudulent method of computing mpg:


As becomes painfully apparent, the numbers are drawn from vapor.

And taking it a step farther, if you take a 540 mile trip then you will use ten gallons of gas, and your real fuel economy for the trip will be 54 MPG.

The reality is, you will purchase and burn ten gallons of gasoline, or five times as much gasoline as you would use if the 230 MPG figure was not complete bull ****.

[Chewbacca]

This is what I found about the completely fraudulent method of computing mpg:


As becomes painfully apparent, the numbers are drawn from vapor.

The validity of suggesting that the car ran for 51 miles on .22 gallons of gas is questionable seeing as the metric assumes that the energy for the first 40 miles appeared out of nowhere. However in terms of consumers going to the pump, most people are easily served with 51 miles of driving per day and thus will have to go to the pump on a 230 mpg schedule.

The methodology they are using doesn't really discuss the fuel economy of the on board generator which was able to power a car 11 miles on .22 gallons of gas (this comes out to a fuel economy of 50 mpg).

The measure is weak because the car essentially uses two fuels but only 1 is being counted in the measurement.

[pattyk]

we are being pushed into electric cars so the flow of taxes to DC goes uninterrupted in the coming years.

[Chewbacca]

we are being pushed into electric cars so the flow of taxes to DC goes uninterrupted in the coming years.

Well that doesn't really make sense....the government makes a pretty penny on the federal Fuel Tax (I think its about 18 or 19 cents per gallon).

[Samm]

But you could make a reasonable estimate.

The volt is publicized as requiring 25 kWh of electricity to travel 100 miles.
The thermal energy content of 1 ton of coal is given as 6150 kWh/ton.

Considering that power plants are able to harness between 40% - 60% of that energy, in the worst case scenario a ton of coal produces 0.4*6150 = 2460 kWh of usable energy.

Given the Volt's published energy consumption of 25 kWh / 100 miles the milage per ton of coal is 2460 kWh / (25 kWh/100 miles) = 9840 miles.

We can also do this with a gallon of gas...

1 gallon of gas contains roughly 36 kWh of energy.

36 kWh/Gallon * 0.4 (usable kWh/kWh) / (25 kWh / 100 miles) = 57.6 miles per gallon (of gas burned at a power plant).

I have no idea what the EPA's metric is based on. But it probably has to do with the fact that you can drive the car 40-50 miles without ever having to use the internal combustion generator (according to the DOT most american's, on average, don't commute more than 40 miles in a given day anyways). So while the car clearly uses energy (it has to come from somewhere), the consumer will on average fill up on a 230 mpg basis.

:eek: Being an engineer myself, I am impressed. ;)

I believe the EPA metric is as you say, based on most trips being less than 40 miles before you plug it in for a charge. They must have some basis for how often the engine would be run because if it was not run at all it would get an infinite mpg (not accounting for evaporation) but they did not provide that information. Using your assumptions, you could calculate it for us. ;)

[johnrocks]

we are being pushed into electric cars so the flow of taxes to DC goes uninterrupted in the coming years.

I don't have a problem with electric,natural gas or any other type vehicle if the people want them and free markets provide them, it's the government intervention that I oppose.

[Samm]

And taking it a step farther, if you take a 540 mile trip then you will use ten gallons of gas, and your real fuel economy for the trip will be 54 MPG.

The reality is, you will purchase and burn ten gallons of gasoline, or five times as much gasoline as you would use if the 230 MPG figure was not complete bull ****.

In fairness, their claim of 230 mpg is only for city driving. If you look at the EPA sticker on a Prius, the mpg for city driving is considerably greater than for highway driving; I'm sure it will be for the Volt as well.

[Dragon1963]

Question why can't GM make all electric vehicles like Tesla Motors does?

http://www.teslamotors.com/

Check out the model S. At $49,000 it costs about as much as a comparable gas powered vehicle.

[Alaric]

Well that doesn't really make sense....the government makes a pretty penny on the federal Fuel Tax (I think its about 18 or 19 cents per gallon).

The state of Oregon has some very bad ideas about that very thing.

[psyko kat]

hmmm, no cross country trips?, just city driving?------it has a 7gal gas tank,..

[Chewbacca]

Question why can't GM make all electric vehicles like Tesla Motors does?

http://www.teslamotors.com/

Check out the model S. At $49,000 it costs about as much as a comparable gas powered vehicle.

Tesla's cars are fully electric which means that if you have to go a long distance you will be forced to stop after 220 miles to recharge. Recharging takes a long time. The Volt at least has an option of running on gas so that a long road trip can be made in a single day.

Those Tesla cars are sexy though.

[Dragon1963]

Tesla's cars are fully electric which means that if you have to go a long distance you will be forced to stop after 220 miles to recharge. Recharging takes a long time. The Volt at least has an option of running on gas so that a long road trip can be made in a single day.

Those Tesla cars are sexy though.

Tesla's have a 45 minute quick charge system on them so it wouldn't be that bad. But still not good for cross country driving.

[johnrocks]

hmmm, no cross country trips?, just city driving?------it has a 7gal gas tank,..

But if you can get 600 miles on that,isn't that better than stopping every 400 miles to fill a 20 gallon tank?

[Chewbacca]

Tesla's have a 45 minute quick charge system on them so it wouldn't be that bad. But still not good for cross country driving.

I don't know if you watch Top Gear, but those guys had some issues with the Tesla Roadster. The quick charge system wasn't quite as quick as publicized and under performance conditions the battery was depleted pretty quickly.

The truly awesome party about all these cars (the Volt included) is that electric motors develop an absurd amount of torque which means that the Volt will probably out accelerate some meaner more powerful cars.

[psyko kat]

But if you can get 600 miles on that,isn't that better than stopping every 400 miles to fill a 20 gallon tank?

not for me, I'll keep my 2001 taurus wagon.

[Dragon1963]

I don't know if you watch Top Gear, but those guys had some issues with the Tesla Roadster. The quick charge system wasn't quite as quick as publicized and under performance conditions the battery was depleted pretty quickly.

The truly awesome party about all these cars (the Volt included) is that electric motors develop an absurd amount of torque which means that the Volt will probably out accelerate some meaner more powerful cars.

Don't have cable so I don't watch Top Gear.

I would venture a guess that for the max. range to be met a Tesla would need to be driven at highway speeds not top. The model S looks like it will be a more down to earth model than the Roadster.

I love electric motors. If batteries ever get to where the output allows you to travel 3,000 miles on a charge at 100+ mph then the internal combustion engine is dead.

[FidelisAdMortem]

So you're spending 40 grand to roughly save 5 grand in gas, and whats the bill for the electric?

[Samm]

But if you can get 600 miles on that,isn't that better than stopping every 400 miles to fill a 20 gallon tank?

They are only claiming a total range of 340 miles.

340 - 40 = 300 miles on gasoline

300miles/7gal = 43 mpg


Not bad, but not particularly outstanding. The strength of the Volt is for city commuting. That is what it is designed for.

[gwhughes]

They've had these for years.....

[sisyphus]

Just a few questions:
How many pounds of petro-chemical plastic products were used to build these Tesla cars?
How much tax financed activity was involved in creating the Volt?
Can either push thru a 2 foot snow drift like an old steel Buick?
Where does the electricity to charge these vehicles come from?
If you have to plug it in, does that count as fuel consumption?

[Chewbacca]

Just a few questions:
How many pounds of petro-chemical plastic products were used to build these Tesla cars?
How much tax financed activity was involved in creating the Volt?
Can either push thru a 2 foot snow drift like an old steel Buick?
Where does the electricity to charge these vehicles come from?
If you have to plug it in, does that count as fuel consumption?

1. Probably about the same as any other modern car. There are going to be plastic bits in pretty much anything we buy.

2. Not anymore than was received by any domestic manufacturer over the last 3 or 4 years. The Volt has been in development for a long time and is actually a successor to the EV-1 that Chevy put out in the 90's (in very limited numbers). This is not some obamamobile that has been cooked up in the last 6 months.

3. The cars electric motors are said to put out 150 horsepower and that electric motor produces more torque than an equivalent internal combustion motor, so the car isn't really a slouch in the power department. That being said, if you need haul loads or traverse some rough terrain this might not be the car for you...its more suited for the suburban jungle than a real jungle.

4. The electricity this verhicle uses comes from two sources. The wall outlet, and an on board internal combustion engine. The cars batteries store enough power for 40 miles of driving, once depleted and the internal combustion engine kicks in. This engine doesn't apply mechanical energy to the wheels but rather produces electrical current that charges the batter and provides electricity for the wheels. This on board motor gets about 50 mpg.

The energy from the wall outlet comes from whatever energy source your local power company happens to use. This could be coal, gas, nuclear, wind, solar, hamsters in wheels. Some quick estimates we did figured that the car is still pretty efficient, getting about 60 mpg from the gas burned in the power plant.

5. No, the MPG the EPA has come up with does not take into account the power in the batteries. If you were to drive the car, starting with a full battery and tank, until you came to a dead stop you would travel 40 miles on battery, and about 350 miles on the seven gallon gass tank for a total milage of 390 / 7 = 55.7 mpg.

The 230 mpg that the EPA came up with accounts for "city" driving conditions. The high milage is accounted for because the average commuter will use hardly any fuel in a given day (most people don't drive more thatn 40 miles a day) and thus, to the consumer, the car gets 230 mpg (because they will be filling the tank on a 230 mpg cycle).

[psyko kat]

I want a moped, if I had a short trip to the store(within 5 miles.)/
I could pull a cart behind it for the groceries...

[sisyphus]

Thank You.
The questions have been answered in part:

1. Plastics replacing steel in large part does date back to the Edsel, but extensive use tends to create unsafe and flammable automobiles. I used to be an EMT and the worst injuries were in cars that were predominately adorned in plastics. Both crushing injuries and burns.
2. The EV-1 was created on a federal grant.
3. 150hp? is that static or dynamic? Still pretty good, but the pics of the Tesla looked like a 2 seater....
4. Mechanical energy converted to electrical energy,converted to mechanical energy... Sounds too Rube Goldburg to be efficient in the long term.
5. The combining of the electric travel and the gas travel as well as not including the 'wall plug time' is cause to say that the numbers are incorrect.
Does your last paragraph imply that the car is plugged in daily?

[CaptainPike]

Thank You.
The questions have been answered in part:

1. Plastics replacing steel in large part does date back to the Edsel, but extensive use tends to create unsafe and flammable automobiles. I used to be an EMT and the worst injuries were in cars that were predominately adorned in plastics. Both crushing injuries and burns.
2. The EV-1 was created on a federal grant.
3. 150hp? is that static or dynamic? Still pretty good, but the pics of the Tesla looked like a 2 seater....
4. Mechanical energy converted to electrical energy,converted to mechanical energy... Sounds too Rube Goldburg to be efficient in the long term.
5. The combining of the electric travel and the gas travel as well as not including the 'wall plug time' is cause to say that the numbers are incorrect.
Does your last paragraph imply that the car is plugged in daily?

Tesla is supposed to be developing a sedan.

[Chewbacca]

Thank You.
The questions have been answered in part:

1. Plastics replacing steel in large part does date back to the Edsel, but extensive use tends to create unsafe and flammable automobiles. I used to be an EMT and the worst injuries were in cars that were predominately adorned in plastics. Both crushing injuries and burns.
2. The EV-1 was created on a federal grant.
3. 150hp? is that static or dynamic? Still pretty good, but the pics of the Tesla looked like a 2 seater....
4. Mechanical energy converted to electrical energy,converted to mechanical energy... Sounds too Rube Goldburg to be efficient in the long term.
5. The combining of the electric travel and the gas travel as well as not including the 'wall plug time' is cause to say that the numbers are incorrect.
Does your last paragraph imply that the car is plugged in daily?

1. I haven't see a Volt or a Tesla (Tesla btw is a seperate company from GM and produces the Roadster and Model S which are purely electric cars) but I would put money on the construction of these automobiles as being very similar to any other modern automobile in their class.

2. I'm sure GM also received some sort of subsidy (under the bush administration) for the R&D that went into the development of the Volt. If the government feels that there are positive externalities to the creation of electric vehicles then they might be justified in providing federal funding to the project.

3. Its 150 for the Volt which is a suburban family car. The Tesla Roadster is a performance car that can out accerlate a Porche 911, its electric motors produce 250 hp.

4. It does sound rather Rube Goldbergian, but EnchantedFrog (in another thread on the topic) posted a quote regarding how the fuel efficiency rating was derived. The quote showed that in the trial the Volt traveled (with 0 power in its battery) for 11 miles using only .22 gallons of gas (gas burned in the internal combustion engine to power the battery and wheels). This amounts to 50 mpg when only running on the internal combustion engine....which is pretty efficient.

5. The understanding is that you plug in the car every night. The 40 mile range of the battery should be sufficient to meet most Americans needs (according to the DOT). The 230 mpg is given as "city" performance. Just like with the Prius, city driving produces better MPG because the car is more likely to be run on its battery rather than tapping into its fuel. The same article touting the 230 mpg rating stated that the car still receives a 100+ mpg rating if the methodology used to evaluate the Prius is used to evaluate the Volt. (The Volt uses a different methodology because its a plug in hybrid rather than a "standard" hybrid).

[chip]

But if you can get 600 miles on that,isn't that better than stopping every 400 miles to fill a 20 gallon tank?

But you cant go 600 miles on a tank

[Creefer]

But you cant go 600 miles on a tank

Its not made for cross country cruising. Its a commuter.

The EPA mileage rating is made specifically for CAFE laws. Its not for cost analysis, but obviously automakers use it as a marketing ploy.

[sisyphus]

I still say that if you plug it in every night, you are consuming resources and therefore the mileage numbers are a fraud.


PS. I used to have an older Chevy that did (official timed) 3.55 for 0-60, and it did better than 24 mpg in the city.

[Chewbacca]

I still say that if you plug it in every night, you are consuming resources and therefore the mileage numbers are a fraud.


PS. I used to have an older Chevy that did (official timed) 3.55 for 0-60, and it did better than 24 mpg in the city.

This point has already been addressed.

The 230 mpg number is not a good indicator of how much energy the car uses, rather it is a good measure of how often the average consumer will have to fill up the tank. Because the average consumer can plug the car in every night and run on the battery, his fill up schedule will be on a 230 mpg basis.

This does not take into account the cost of charging up the battery.

The Volts battery holds roughly 16 kWh of power. The cost to fully charge the car is going to be dependent on how much you pay for electricity. On average Americans pay 11.6 cents per kWh, so a full charge every night will run you $1.87. It will obviously be less if you do not fully expend the battery during the day. That $1.87 gets you 40 miles of driving in a day. By comparison the average cost of a gallon of gas is about $2.06 and the average car does not get 40 miles for that gallon.

The above analysis is on a cost basis, where the Volt does perform pretty well. On a total energy used basis the Volt is really no better than a Prius.

Back in the thread is the full break down of the estimates, however the Volt gets roughly 57 mpg for every gallon of gas burned at a power plant. The on board generator was tested as getting 11 miles / .22 gallons or 50 mpg (this is from the test that determined the 230 mpg). Thus the true energy cost of the car is somewhere between 50 mpg and 57 mpg depending on usage.

So yes the numbers are "a fraud" if you are looking at the total energy cost of the car. The numbers are accurate if you are looking at how often a person will have to fill up his car at a petrol station.