While messing with the numbers lets up'em

stubeeef

macrumors 68030
Original poster
Aug 10, 2004
2,702
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Link


Well-known motorists club AAA says many cars and trucks it road-tests fall far short of their government fuel-economy ratings.

Using that disappointing fuel economy data from hundreds of road tests in what AAA calls real-world driving, the organization plans to endorse legislation to be introduced Thursday that would require the U.S. Environmental Protection Agency (news - web sites) to overhaul its gas-mileage tests.

Environmental groups have argued for years that mileage labels are bogus, but it is significant that AAA is throwing its influence behind the bill to change them. (Related: Drivers irked as mileage fails to add up)

"There's no doubt that it helps. And it highlights the fact that it's just common sense - providing consumers with accurate information," says David Friedman, a research director for the Union of Concerned Scientists. UCS strongly backs legislation to require realistic mileage ratings.

AAA data come from tests done by drivers across the country "getting groceries, getting stuck in traffic jams, driving the same way you would," says AAA spokesman Mantill Williams.

The organization concedes that its tests aren't scientific but insists the results are representative.

Among vehicles that were farthest off of EPA: 2004 BMW Z4 sports car, which AAA says hit just 14.5 miles per gallon in combined city-highway use, vs. 24 mpg EPA rating; Chevrolet TrailBlazer SUV, 13.6 mpg in AAA testing vs. 17 mpg EPA rating; Chrysler PT Cruiser, 17.5 mpg from AAA vs. 25 mpg EPA rating.
The so-called Fuel-efficiency Truth-in-Advertising act would require EPA tests to "reflect modern driving patterns and experiences, specifically speed and highway-vs.-urban driving," says Rep. Nancy Johnson (news, bio, voting record), R-Conn., co-sponsor of the bill with Rush Holt, D-N.J. "Those are no-brainers," she says.
This is news, but probably a bit political. Here are both R and D working to change it, the upside here? Is that manufactures will actually have to build more effecient cars and trucks, they have been scamming to make their CAFE numbers. This is a benefit for everyone! But while they are going to require a more accurate test, why not put in an increase for CAFE requirments.
 

miloblithe

macrumors 68020
Nov 14, 2003
2,072
28
Washington, DC
I seem to remember some vehicles actually doing better than their EPA ratings as well, but I can't think of where I might have read that. It does seem unlikely looking at that article, in which all the cars mentioned are drastically underperforming.

This does sound like a good effort, although any serious downgrading of most cars fuel economy estimates by the government would likely be accompanied by a drop rather than a raise in CAFE standards. Another fair point is that fuel economy depends greatly on the way people drive. You could probably get 24MPG in a BMW Z4, but very few people would be willing to drive that way, especially the kind of people who would buy a BMW Z4. Still, it would make sense to have the estimates reflect "average" driving rather than ideal driving (with respect to fuel economy).
 

wordmunger

macrumors 603
Sep 3, 2003
5,124
2
North Carolina
My volkswagen passat regularly gets 29 MPG in suburban driving (some traffic, some highway). I believe it was rated at 24 city/ 31 highway. I do get about 31 on long highway drives. Even in bad traffic, it never gets as low as 24.
 

MongoTheGeek

macrumors 68040
One of the best demonstrations I can think of between measured and real numbers was on MythBusters. They bring good scientific methodologies along with the penchance for destruction.

Once they attacked the myth of AC versus windows down on MPG. The first test they hooked up a meter that read the oxygen sensor in the car which is how the EPA measures mileage. Essentially it measured the airflow into the engine and then based on stochiometric principles deduced fuel consumption. AC won by a good sized margin

The second test they ran 2 identical cars with a fixed amount of fuel until they ran out. Windows down won by a good sized margin.
 

stubeeef

macrumors 68030
Original poster
Aug 10, 2004
2,702
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MongoTheGeek said:
One of the best demonstrations I can think of between measured and real numbers was on MythBusters. They bring good scientific methodologies along with the penchance for destruction.

Once they attacked the myth of AC versus windows down on MPG. The first test they hooked up a meter that read the oxygen sensor in the car which is how the EPA measures mileage. Essentially it measured the airflow into the engine and then based on stochiometric principles deduced fuel consumption. AC won by a good sized margin

The second test they ran 2 identical cars with a fixed amount of fuel until they ran out. Windows down won by a good sized margin.
Very interesting!
 

ziwi

macrumors 65816
Jan 6, 2004
1,087
0
Right back where I started...
One can only hope that this will make the auto makers change, but I for one will not hold my breath. The mileage that we get now is not much different from 20 years ago - that is really sad. What is more sad is that we are still dependant on the fossil fuels. This may make a change and that is good, but does it just make us rely on these types of fuels longer than we should?
 

miloblithe

macrumors 68020
Nov 14, 2003
2,072
28
Washington, DC
MongoTheGeek said:
One of the best demonstrations I can think of between measured and real numbers was on MythBusters. They bring good scientific methodologies along with the penchance for destruction.

Once they attacked the myth of AC versus windows down on MPG. The first test they hooked up a meter that read the oxygen sensor in the car which is how the EPA measures mileage. Essentially it measured the airflow into the engine and then based on stochiometric principles deduced fuel consumption. AC won by a good sized margin

The second test they ran 2 identical cars with a fixed amount of fuel until they ran out. Windows down won by a good sized margin.
What sort of speeds where they running these tests for? Obviously, the higher the speed, the worse the windows-down strategy will be.
 

craigdawg

macrumors 6502
Mar 8, 2004
360
0
Sactown
I predict the auto industry will:

1. Spend a boad load of cash to lobby Congress against this act
2. Employ some scare tactics about how much more automobiles will cost and how many jobs will be lost as a result of this act
3. Change the subject and talk about how they're developing hybrids and fuel cell vehicles, etc.
4. Ultimately maintain the status quo

I hope I'm wrong.
 

MongoTheGeek

macrumors 68040
miloblithe said:
What sort of speeds where they running these tests for? Obviously, the higher the speed, the worse the windows-down strategy will be.
45 mph iirc.

Dynamic resistance goes up with the square of the velocity so yes, windows down would get progressively worse, but the difference in drag coefficient may not be constant and I can actually envision some scenarios where the windows down might actually lower drag coefficient by tripping the flow from laminar to turbulent.
 

mactastic

macrumors 68040
Apr 24, 2003
3,681
665
Colly-fornia
miloblithe said:
What sort of speeds where they running these tests for? Obviously, the higher the speed, the worse the windows-down strategy will be.
I saw that one too, and I didn't think it was fair of them to make the claim without testing at various speeds. Think 5MPH. AC is a clear loser there. Windows open would create so little drag as to be negligible. 150MPH? Waaaay different story. Also most people don't drive with all 4 windows down, how would only 1 or 2 windows down perform?

I did feel sorry for the guy who had to run with the AC on full blast for that many hours.... Brrrrrr.
 

Lacero

macrumors 604
Jan 20, 2005
6,639
2
I read about advances in automotive technology such as the use of ceramic engines that could mean better gas mileage and near lifetime performance without the need for an oil change. However, the car manufacturers want to keep that technology off the market because it would mean their business could not sustain profitability for their investors. Car manufacturers and oil industries have a lot at stake in keeping low MPG on cars built today.
 

MongoTheGeek

macrumors 68040
mactastic said:
I saw that one too, and I didn't think it was fair of them to make the claim without testing at various speeds. Think 5MPH. AC is a clear loser there. Windows open would create so little drag as to be negligible. 150MPH? Waaaay different story. Also most people don't drive with all 4 windows down, how would only 1 or 2 windows down perform?

I did feel sorry for the guy who had to run with the AC on full blast for that many hours.... Brrrrrr.
Thing is that AC lost at 45.

45 is a good representative speed. Average speed in many areas during rush hour, Speed limit on many secondary streets.

There are so many variables to test that would have made for a really dull month of taping and a really dull hour of TV.
 

MongoTheGeek

macrumors 68040
Lacero said:
I read about advances in automotive technology such as the use of ceramic engines that could mean better gas mileage and near lifetime performance without the need for an oil change. However, the car manufacturers want to keep that technology off the market because it would mean their business could not sustain profitability for their investors. Car manufacturers and oil industries have a lot at stake in keeping low MPG on cars built today.
The Oil companies are happy with the low MPG. The car companies for the most part don't care. Ceramic engines are a pain to manufacture and maintain and the average consumer won't double the price of their car just to get an extra 25% fuel savings.

Car companies don't like CAFE standards because it forces them to make and sell small light cars at a loss so that they can make the cars that people actually want to buy.

Engineering cars are a delicate balancing act between price and features, and mileage. They could make a car out of lighter materials, composites, etc but that would increase the price. There are also limits to how light you can make the car and still have it be "safe." Look at the corvair. It was a light car with good milage and was pulled off for safety issues. The same thing for the pinto. It had a lighter gas tank for better cost and mileage. Blame Ralph Nader, for crappy mileage of cars today.
 

andiwm2003

macrumors 601
Mar 29, 2004
4,339
400
Boston, MA
MongoTheGeek said:
Thing is that AC lost at 45.

45 is a good representative speed. Average speed in many areas during rush hour, Speed limit on many secondary streets.

There are so many variables to test that would have made for a really dull month of taping and a really dull hour of TV.
thing is also they tested it on large SUVs where the increased winddrag of the open window doesn't matter a lot in comparison to the overall winddrag.

doing that test on an more aerodynamic car may change the outcome. here the impact of the open window could be huge and AC could turn out to be more fuelefficient.

my 2 cents,

andi
 

KingSleaze

macrumors 6502
Feb 24, 2004
410
0
So. Cal
miloblithe said:
What sort of speeds where they running these tests for? Obviously, the higher the speed, the worse the windows-down strategy will be.
That was the problem with the results that they 'demonstrated' on Mythbusters IMO. During the first test they ran at 45 mph. During the second test, they ran at 30mph.
They need to run it on a superspeedway and at higher speeds.
 

mactastic

macrumors 68040
Apr 24, 2003
3,681
665
Colly-fornia
MongoTheGeek said:
Thing is that AC lost at 45.

45 is a good representative speed. Average speed in many areas during rush hour, Speed limit on many secondary streets.

There are so many variables to test that would have made for a really dull month of taping and a really dull hour of TV.
I don't care which one lost or won, I have no horse in that race. I'm just commenting on the somewhat flawed methodology to arrive at the conclusion, disseminated to their viewers, that windows down is more efficient. They needed many, many caveats to make that claim, and IMHO they didn't provide them.
 

Dont Hurt Me

macrumors 603
Dec 21, 2002
6,055
6
Yahooville S.C.
craigdawg said:
I predict the auto industry will:

1. Spend a boad load of cash to lobby Congress against this act
2. Employ some scare tactics about how much more automobiles will cost and how many jobs will be lost as a result of this act
3. Change the subject and talk about how they're developing hybrids and fuel cell vehicles, etc.
4. Ultimately maintain the status quo

I hope I'm wrong.
This sickens me and i think you will be right. As foreign automakers work on fuel economy the big three are doing the same garbage from the 70s....Big V-8s and 4 x 4s and then spinning the numbers. We should demand 30 mpg from vehicles and those that cant should pay the gas guzzler tax. There just isnt a reason for everyone driving 250 hp cars and trucks. Problem is Congress works for them not us. Its ashame that we now have bigger gas hogs then we did in the 70s and Congress encouraged this or rather the automakers encouraged Congress through lobbiest and donations. Congress is in the big threes pocket.
 

wdlove

macrumors P6
Oct 20, 2002
16,568
0
The Big three may become less relevant with time. Toyota has already moved into the Big 3. GM and Ford had losses in January, they blame it on weather. They should learn to make cars that people want.
 

Roger1

macrumors 65816
Jun 3, 2002
1,152
0
Michigan
I remember listening about this on npr. I guess when the auto makers do the milage test, they are required to do them at a specific speed, under specific circumstances.

My own opinion is we need to start dropping diesel engines into everything, and run them on vegetable oil.
 

aloofman

macrumors 68020
Dec 17, 2002
2,206
0
Socal
The narrow meaning of EPA mileage standards is not really news, as people have been noting discrepancies for a long time. The main problem is that the tests do not reflect how most people drive their cars. Most people accelerate and brake more than necessary in city driving, for example. For this exact reason it's difficult to set a standard for what mileage a car "should" get when so much depends on the driver's habits, driving conditions, tire choice, engine maintenance, etc. I don't know if there's a change that the EPA could make that would make the tests more realistic.

One thing I'm pretty sure of though, is that the carmakers all use similar tricks to make sure their cars get the best possible results in the EPA's mileage tests. From this perspective, I'm not sure they care that much whether the EPA changes their test, since they'll just rejigger their specs to maximize their results again. (Although there might be a truck vs. car discrepancy there, since Ford, GM, and DC, depend much more on truck sales than other automakers in the U.S. market.)

And I really doubt that the automakers are holding back exotic technologies solely to rip people off. In the short term, they don't use ceramic engines because they would raise the production cost so much that they couldn't sell them. There's a limit to how far this argument can go though, since they made similar complaints every time they were required to include catalytic converters or airbags, saying that it would cost their customers too much.
 

Moxiemike

macrumors 68020
Jan 1, 2002
2,437
0
Pittsburgh, PA
Dont Hurt Me said:
This sickens me and i think you will be right. As foreign automakers work on fuel economy the big three are doing the same garbage from the 70s....Big V-8s and 4 x 4s and then spinning the numbers. We should demand 30 mpg from vehicles and those that cant should pay the gas guzzler tax. There just isnt a reason for everyone driving 250 hp cars and trucks. Problem is Congress works for them not us. Its ashame that we now have bigger gas hogs then we did in the 70s and Congress encouraged this or rather the automakers encouraged Congress through lobbiest and donations. Congress is in the big threes pocket.
Amen. I totally feel you 100%. I'm amazed and surprised at how my 03 Saab performs, and it bugs me a bit that saab, one of the last car makers (well, they are GM, but their line at least...) with no SUV is now introing the 9-7. Blah.

I'll tell you, we've been slammed with snow the past week, and on Thursday I had to drive my dad's ford taurus to go to some of my photo assignments. It was darn stressful. I got my saab back, and was outpacing the big, bad made for the snow SUVs.

It's just like the Canon vs. Nikon debates I get in every now and then--it's all about the driver! So if a soccer mom can't pilot her massive Escalade or Suburban in the snow... chances are she's not doing a good job driving in better weather either.

So the estimated MPG in her case goes down. Maybe from 17/22 to 13/19. What a waste! OTOH, my Saab, rated at 25/31, and a manual tranny, goes better in the snow with me driving, so no need for an SUV and I often get BETTER than the 25/31 the EPA predicts. On a drive to DC 2 summers ago, I got 37 mpg on the way down. Normally, my mpg is around 27 in mixed conditions. Again, i'm sure it has something to do with my 12 years of driving experience solely on manual transmissions. (I get confused in automatics. yawn.)

So i think we need a gas guzzler tax, we also need special licensing to drive an SUV. It's a specialized vehicle, much like a motorcycle. I think anything higher than a passenger car should require additional licensing, with high per year renewals. Having driven some smaller SUVs for friends/family, I can honestly say that driving even a small one is different enough of an experience that it should be regulated different.

It's a shame that companies have really gone back to the big ol' gas guzzling days, but I think that American car quality is going up, simply because these guys could NEVER compete with the Europeans or Japanese in efficient carmaking. We just don't have the mentality in America for things like efficiency and common sense. If we did, people would realize that for most city driving, one can get by with a Honda Civic hybrid, or one of the more efficient european models, aka Saab 9-2x, 9-3, BMW 3 series or something like the Subarus or gas Hondas.

America just cannot design cars like that. GM, Ford and Chrysler have to buy the likes of Saab, Volvo and Mercedes Benz just to get close. Shame.

I hear whisperings of a hybrid Saab 9-3 in the future. I'll jump on that in a heartbeat :)
 
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