Question about MPG

wrote in message <snip>


The prius recovers energy whether coasting to a stop or braking to a stop.
>This is evidenced by the very low capacity of the Prius battery pack, only able to power the >car for a few seconds at full output, which in turn explains why Toyota provided no facility to

What is evidenced by the battery packs capacity? The battery pack stores recovered energy. It has the capacity to do precisely what Toyota intended.

Of course, so does lugging around a diesel engine.

Steve, this discussion would make more sense if you gave us the make and model of the particular diesel you are comparing to the Prius. Having that, we can compare the specifications of that vehicle with the specifications of the Prius. Let's face it, you have made a lot of claims in this discussion but you are the only one who possesses both sets of specifications.
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wrote in message

I understand 'coasting to a stop' as being what happens when you release the accelerator (gas) pedal - on a level road, the car slows gently owing to friction from the air, rotating surfaces and tyre hysteresis, and ultimately engine braking, depending on the gear selected (I know the Prius has CVT so that's not applicable in the same way as a normal gearbox). 'Braking' is deliberate slowing of a much greater magnitude. I'd be surprised if the Prius regenerated when 'coasting', since this would inevitably slow the car (like deliberate engine braking does) much more than just taking the foot off the pedal.

Quite, which is just enough to give a short acceleration boost or run some utilities with the IC engine off, but not enough to operate as a true electric car for any distance. This isn't a criticism, just a clarification. Believe it or not, there are people out there who think the battery somehow contributes a net positive energy to the car.

Not to the same extent, the weight premium for a modern diesel (even including its heavier starter, turbo, etc) over a comparable-output gasoline engine is much less than the Prius battery pack etc.
<snip>

I'm not actually making a comparison with a specific diesel, just trying to find out (see my first article in this thread) whether the mpg figures claimed by Toyota and some (naturally) pro-Prius subscribers to this forum are truly based on real measurements of road mileage and of fuel consumed (measured by what you put in the tank), or whether they are just what the 'computer' (OK, not a trip computer) on the dash says. That's all.
Clearly, there will be people (especially those who have bought Prius cars) who are very anxious to claim an optimistic figure. All I'm pointing out is that if you want really good fuel efficiency, we've been doing it in Europe with diesel cars such as the '3 litre' VW Lupo, for years. That's three litres per 100km which equates to about 94 mpg (imperial) or, say, 75 mpg (US gallon), and this is readily achievable even on long-distance driving. VW are bringing out even more economical models. In contrast, quoting from Wikipedia, "By the European method, the combined fuel economy of the Prius is 4.3 L/100 km or 55mpg (US)".
http://en.wikipedia.org/wiki/Toyota_Prius

Again it's not a matter of specifications but of principle. I'm just curious to know whether the claims of fuel economy are based on real numbers, or the say-so of a dial on the dash.
For the record, my own car is a Skoda Octavia with a 2-litre diesel. Keeping a log of every litre of fuel I've ever put in it, over 13,438 miles it's used 1,340 litres and so averaged 42.2 mpg (imperial). This is a good bit worse than a Prius, but it's a much bigger and more capable car, and at least I know that the figure is accurate (as accurate as the fuel pumps at the forecourt and the odometer, which I have checked against the motorway mileposts on a long run). By comparison, the trip computer reads about 7% optimistic on average.
SteveP
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wrote in message

You should drive a Prius. Toyota did a great job. The "feel" of the charging that takes place while coasting to a stop is identical to the feel of engine braking in a conventional car. A "B" (engine braking) shift position is provided if actual engine braking is needed for long hills. Yes, I was surprised too.

No, it can drive as a true electric car for a significant distance. We Prius owners call this the "stealth mode". Frankly, you need to rent one for a few days. From what you write here it is clear you are describing how you *think* the Prius works, not how it does work.

The tiny, 3-door Lupo hardly compares to the mid-sized, 5-door Prius.

I tried. They aren't comparable, one being a mini, the other being a mid. Couldn't find the Lupo emission figures.
Let's face it, you have made a lot of

Yes, it is a matter of specifications. Not every family of five will fit on a mo-ped. Rent one. You are trying to compare apples to oranges but you've never eaten an orange.
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<snips>
I can't fault your logic - I am speaking from what I've read, not first hand experience. However, despite our interesting debate (for which I thank you) I still haven't seen the real-world figures requested by the OP.
Steve
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Steve, "real world figures" are anecdotal and largely depend on individual driving skills and habits. Your real world differs from mine. The same Prius will produce much better mileage for the husband than for the wife or visa versa. Where I live many of the highways have a 55 mph speed limit. This is very close to the speed at which our Environmental Protection Agency tests cars to determine the figures they publish, the ones that are by law posted on the window of every new car. If you drive 55 you will, on average, achieve the published figures.
As a consequence, the only fair comparison is of the EPA figures for vehicles of the same size. Deviations from the published figures will affect both vehicles. In fact, a number of people have "tested" the Prius and concluded it does not achieve the EPA figures in their "real world" scenario. They tested the Prius because they were astounded by the published figures and you will note they don't compare their "real world" results with the "real world" results of some other car that underwent an identical "real world" test. The same driver's "real world" would have a proportional effect on whatever car they tested. Also, a number of people have made a hobby out of exceeding the EPA figures. It is important to remember that a 10% reduction from 50 mpg is 5 mpg while a 10% reduction from 20 mpg is 2 mpg. 10% is 10%, but some people can't comprehend that.
I've concluded that publishers who whine about this "real world" of theirs are people who live in a world that doesn't care about either pollution or conservation. People who do will meet or beat the published figures. After all, this is what "Environmental Protection" is all about.
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Be surprised then because it does--unless you're on a hill and the force of gravity causes the car to keep from slowing down.

It can go a mile or two on battery alone. Quite often while driving under 42 MPH, you're driving solely on battery power.

Fuel economy is only part of the equation; the other part is cost of the fuel.
And those are considerations that are separate from pollution.
--
Stop Mad Cowboy Disease: Impeach the son of a Bush.

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How many of these get equal or better fuel economy while meeting SULEV emissions requirements? Prius was designed more to minimize emissions than to minimize fuel consumption.
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cars)
out is

Europe
mpg
driving.
from
Prius
I understand that - but if you refer back, my initial question focussed merely on comparisons of fuel consumption, since we don't have the SULEV stuff in Europe (with a few exceptions, such as central London, where the Prius is exempt from the Congestion Charge).
Steve
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On Wed, 16 Aug 2006 10:26:17 -0500, richard schumacher

Too bad the same can't be said for a retarded fool like you, dick.
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.....YAWN.....
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Actually quite a few. One of the problems with an idling engine is the drop in exhaust gas temperature cools the catalytic converter. When the catalytic converter gets too cool, it doesn't work.
By turning off the engine, the catalytic converter remains at operational temperatures, it isn't cooled by idling exhaust gas. This keeps the emissions low.
Bob Wilson
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The Prius doesn't use a trip computer; it measures the gas being injected into one cylinder, multiplies that by four, and divides it into the miles travelled.

So? Diesel is dirty; it pollutes. There are a number of states (California, and most New England states, and New York) in the US where the sale of diesel automobiles, SUVs, pickups, and mini-vans is prohibited because of that.
--
Stop Mad Cowboy Disease: Impeach the son of a Bush.

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wrote:

Ummm, using a computer to calculate and display all this?

I'm afraid you're out of date. "Euro IV" standard diesels are exceptionally clean-burning, have multiple catalysts, and many new cars have particulate traps. The lower CO2 emissions outweigh the slight (inevitable) increase in NOx.

And also impractical because there is no infrastructure for fuelling millions of passenger cars with diesel? Surely the real problem is that our American friends have only recently come to appreciate the true cost of hydrocarbon consumption (political as well as economic and environmental) and haven't woken up to diesel for cars yet. That's also the main reason why the Prius has a gasoline engine. Believe me, you will wake up, and diesel hybrids will come.

Something we can agree on!
SP
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Yes and no. Extensive reporting yields a couple of percent difference between the computed mileage and the actual mileage. Tire diameter changes with tread wear contribute to errors in both computed and manual calculations. Fuel pump pressure variations contribute to errors in the computed mileage. Frankly, both methods are so close as to render further discussion pointless.

They are certainly welcome to sell these in the U.S. once they meet California's strict emission standards. Haven't reached that point yet.

I would estimate 95% of our service stations have diesel pumps. Our trucking industry is about 100% diesel. There are lots of diesel pickup trucks on the road and some diesel cars. Where I live, gas was $2.99 and diesel was $3.19 when I last filled my Prius.
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But not a "trip computer".

The infrastructure is there; a service station less than three miles from my house sells diesel. There are diesel trucks that travel all over the country, even in states where diesel cars, SUVs, mini-vans, and pickups are lot allowed to be sold. There are service stations that sell diesel to them and to those cars, etc., from out of state traveling through the state.
--
Stop Mad Cowboy Disease: Impeach the son of a Bush.

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Steve Pardoe wrote:

Surely the real problem is that your American friends have /not/ /yet/ come to appreciate the true cost of hydrocarbon consumption, either political or environmental. A governing regime that is thoroughly corrupted by greed for oil profits is doing its best to keep people from thinking about that -- doctoring research, trying to gag scientists, announcing that more study is needed to determine whether global warming is real, in short, doing all that it can to sow doubt as to whether reducing fossil fuel consumption is a desirable thing. GM -- let us all bow our heads and pray that it goes bankrupt soon, taking Ford with it! -- is doing its part by offering to buy gasoline for those who buy its 9 MPG SUV's.
We will find out in November of 2006 -- and in November, 2008 -- the extent to which Americans understand anything that is going on around them.
Davoud
--
usenet *at* davidillig dawt com

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Steve Pardoe wrote:

So what about Euro IV? Diesels are under a different emissions rating plan than petrol (gasoline) vehicles, mostly to diesel's benefit, under the Euro standards.
http://www.dieselnet.com/standards.html to compare different emissions:
Euro standards: http://www.dieselnet.com/standards/eu/ld.html
Euro 4, Diesel CO 0.50 g/km = 0.807 g/mi HC (not rated) HC+NOx 0.30 g/km = 0.483 g/mi NOx 0.25 g/km = 0.402 g/mi PM 0.025 g/km = 0.040 g/mi
Euro 4, Gasoline CO 1.0 g/km = 1.609 g/mi HC 0.10 g/km = 0.161 g/mi HC+NOx (not rated) NOx 0.08 g/km = 0.129 g/mi PM (not rated)
remembering to convert from g/km to g/mile is helpful. 1 gram / kilometer = 1.609344 grams / mile
The US Tier2 regs do not separate the fuel type, but treat the fuel and the car as a whole system. Because of the higher NOx and PM of diesel fuel, they'll get classified in a lower Bin because of their emissions, right next to an unclean gasoline car.
You can also view the US Tier2 and Tier 1 Emission standards here: http://www.epa.gov/greenvehicle/detailedchart.pdf
The US Prius meets the US Federal emission standards Tier 2 Bin 3, and CA emission standard SULEV II (AT-PZEV). (It's the same car sold with 50-state emissions, just that some states do not recognize the CA emission categories.) As an AT-PZEV, it must be guaranteed for 15 years/150,000 miles to meet the emissions standards, plus also have a fully-sealed, zero emissions fuel system (no loss of evaporative emissions). http://www.fueleconomy.gov/feg/noframes/22016.shtml
US Tier 2 Bin 3, Emission limits at 100,000-120,000 miles NOx = 0.03 g/mi NMOG = 0.055 g/mi CO = 2.1 g/mi PM = 0.01 g/mi HCHO = 0.011 g/mi
CA SULEV II, Emission limits at 100,000-120,000 miles NOx = 0.02 g/mi NMOG = 0.010 g/mi CO = 1.0 g/mi PM = 0.01 g/mi HCHO = 0.004 g/mi
My reading is that the Euro standards are very strict on CO, but if you ignore that compound the Euro4 petrol standard is about a Tier2 Bin6, and the Euro4 diesel standard is about a Tier2 Bin9c. But I could be wrong on my matching of data...

Most filling stations have diesel pumps. The bigger problem is that we're only starting to phase in low-sulfur diesel ( <15 ppm), which Europeans have had for some time. (sulfur pollutes emission control systems and leads to higher emissions.) I suppose once US diesel is as clean as European fuel, we might start seeing more of the advanced diesels the rest of the world has.
Of course, many Americans remember diesels of the past - unreliable in winter, and belching large plumes of filthy smoke... That conception will be hard to break for future offered diesels.
(I'll also note that US OSHA (Occupational Health and Safety Administration) has various regulations on diesel exhaust, but I haven't seen the quite so many for gasoline (mainly just for auto repair shops or drive-through restaurants). http://www.osha.gov/SLTC/dieselexhaust/standards.html )
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I have a four week old 2006. I get about 48 around town (suburban) and on the highway, but somewhat better in hilly rural terrain (up to 52). I noticed that others have experienced this as well. Tires are still at original setting. In a real city it drops to around 46.
I am trying to see if different brands of gas effect mileage. My latest tank of Getty seems to be doing better than the last tank (Shell). I am in upstate NY.
Mark
Michelle Steiner wrote:

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snipped-for-privacy@nospam.org wrote:

Who is me? I missed your name. And your e-mail address is snipped-for-privacy@nospam.org? There are ways of posting your e-mail address so that it is not machine readable...
Davoud
--
usenet *at* davidillig dawt com

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I can tell a Prius isn't in your future. Buy something else which already has a bad reputation that can't suffer from more negativity. mark_
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