Posted on 07/13/2010 8:04:34 AM PDT by Sub-Driver
Drop 'miles per gallon' as fuel measure, says US National Research Council
The US National Research Council has said that "miles per gallon" should not be used on its own in measuring a car's fuel use, backing a green motorist's group which called the measure "stupid".
By Tom Chivers Published: 2:57PM BST 13 Jul 2010
The NRC said that the measure caused consumers to overestimate the importance of changes at high miles-per-gallon (mpg) values, and underestimate it at small ones. Particularly, it says: "Fuel economy data cause consumers to undervalue small increases (1-4 mpg) in fuel economy for vehicles in the 15-30 mpg range."
The panel urged that fuel use be displayed as fuel consumed - perhaps as volume of fuel used per 100 miles - alongside the traditional miles-per-gallon measure. This standard is used already in Europe, with fuel use being given in terms of litres used per 100 kilometres travelled.
An environmental motoring website, GreenCarReports.com, welcomed the move, saying that it had been calling for the change for over a year and describing the mpg measure as "stupid". It asks the question: "Do you save more gasoline by going from 10 to 20 mpg, or going from 33 to 50 mpg?"
(Excerpt) Read more at telegraph.co.uk ...
A Chevy HHR. Don’t know what it stands for....just that I think it translates into “do not buy the low profile tires and wheels....they will cost you a fortune.)
At this point, I’m suspicious of ANYTHING the Greenies put forth as policy.
But at that fuel usage it can push a container ship at 29 miles per hour. How far it goes in one second: 29mph / 3600 = .008, so it uses one gallon to go .008 miles. That's a gallon to push it only 43 feet.
Times 157,000 tons = 1,254 ton miles per gallon (counting the deadweight tonnage, the weight of all cargo, fuel, etc., not the ship itself).
But the problem is we don’t know how you relate to their estimates. How much of car A’s 3500 is insurance and how much better or worse would your insurance rate be compared to their estimate? How much of car B’s 3200 is it mechanical maintenance and how does you mechanic compare? If it turns out $2000 of A is insurance and your rates would make it $1000 and $2000 of B is maintenance and you’ll be taking it to them so that number is spot on then A is actually cheaper for you and their numbers did nothing other than steer you wrong.
That’s what I keep telling you, if they put numbers like that on the sticker they’d be FICTION, made up, having little if any bearing on you me or any other prospective buyer. Best to leave them off, since they’d be 100% meaningless junk numbers anyway. And worse each dealer would be using different standards for their math, so whatever “correction” you’ve figured out at one place doesn’t apply at the other. They wouldn’t be a suggestion, tool or ballpark; they’d be made up, useless and pointless.
But I would say that most people aren't just looking at one car. They are looking at multiple cars, which car do they want the most? Unless you're super-rich, the cost of the cars will come into play. I'm looking at Cars A, B or C, so which one do I get? When they say 15, 20 and 28 mpg on them I'll get a warped sense of cost between them. I love A, like B, somewhat like C. How much do I save going A-B? Is that worth it to me? How about another step to C? Is that worth it? It looks like an even bigger savings, 8 mpg, so I might get C even though I don't like it as much.
But that's really 6.7 vs. 5 vs. 3.6 gallons/100 miles. Out of my wallet that will be 1.7 gallons or 1.4 gallons different. Going to C doesn't save me as much as I thought when looking at mpg. I'll stick with B.
Forget about the environmental aspect. The less fuel we use, the less dependent we are on foreigners. The less fuel an individual uses, that's more money in the bank. Anything that expresses that more accurately for the buyer is a good thing. I'm not saying everybody should start thinking in terms of gallons/100 miles, but in terms of an informed consumer it would be better to have that on dealer stickers than mpg.
Yes, multiplication is easier than division, so 20x25 = 500 miles is easier than 20/0.04= 500 miles (25 mpg is 0.04 gallons per mile).
And yes, there are times when you want to know how far you can go before you have to re-fill the tank. Except that since you don’t usually know precisely how many mpg you are getting, it’s easier to watch the gas gauge to determine when you have to re-fill the tank.
And of course, any manufacturer which can provide a digital readout of the MPG you are getting can also easily give a button to switch to Gallons per mile, so you could have both pieces of information.
But the MPG rating of a car exists to compare different car performance, not to help you figure out on a particular trip whether you need to stop for fuel. And for comparisons, the important thing is how much more or less will it take to drive a specific distance, not how much farther or less far you can drive on a tank of gase.
It’s not the miles that cost you money, is the gallons. And it’s much easier to compare the cost of gasoline between cars when provided with the gallons/mile number.
This is what happens when people that don’t understand basic math are put in positions of power.
The "trick question" isn't really a trick question at all. And the reason that so many people get it wrong is the same reason that too many people think that an income tax rate increase from 10% to 15% means a 5% increase in their taxes -- namely most people are STUPID in math.
Any "informed" consumer that is getting into as detailed an analysis as you are describing would have a good idea of his annual miles driven. Estimating annual fuel consumption based on annual miles driven is actually easier (one calculation) by dividing annual miles by the miles per gallon figure to determine annual gallons consumed as opposed to dividin annual miles by gallons per hundred miles and then multiplying by 100 (two calculations).
“not how much farther or less far you can drive on a tank of gase(sic).”
Apparently you don’t get out town much.
I think you are both thinking more practically than the norm. I know what I want to do and how many miles I want to drive. The MPG figure will help me predict how much that will cost me, and is useful to me for that reason. But, as you have both pointed out, it will is not the best figure to use to make optimal decisions about minimizing my fuel consumption and carbon footprint. The American preference for the MPG figure indicates to me that Americans, in general, are more worried about their own plans, and don’t give a hoot about their carbon footprint.
Needless to say, the bunny huggers at the US National Research Council (whatever that is) don’t share that view.
No, MPG more easily answers "how far can I go on the gas I have?" Gallons/100m more easily answers "how much will this trip cost me?"
But, as you have both pointed out, it will is not the best figure to use to make optimal decisions about minimizing my fuel consumption and carbon footprint.
Both of which are equivalent to "how much will this cost me?"
You forget, due to us thinking base 10, dividing by 100 is not computationally intensive, just mentally shave off the last two digits. It's an operation that doesn't take any time. It's like in a computer where a divide is normally pretty computationally intensive, requiring several CPU cycles. But dividing by two is a special case since computers think binary, so it requires only a right shift of the bits (if you don't care about remainder).
Say I drive 15,000 miles per year, car gets 4 g/hm, that's 4*150=600 gallons per year. Say I drive 15,000 miles per year, car gets 26 mpg, that's (opens the calculator to do division) 576 gallons per year. With MPG you have to divide by some number, usually one you can't quickly do in your head. Gallons/100miles has already done that division for you, leaving only multiplication.
But this is all about the number on the dealer sticker being more meaningful, and gphm definitely is for that purpose.
How do you figure? If I want to drive 65 miles, and my car gets 30 MPG, I know it will take a little over two gallons. Doesn't get much easier than that.
But to use the 3.3 G/100M figure, I have to first figure that 65 is .65 of 100 and then multiply 3.3 by 0.65. All this gives an accurate figure, but I find using the MPG better for arriving at the "a little over 2 gallons" result.
Your milage may vary, of course.
But my larger point is that one type of measure will predominate in the USA and another in Europe, because Americans and Europeans think about things like consumption differently. This does not mean that the US system is "stupid". It just means that Americans don't choose to be straight-jacketed into European rationing-based thinking.
Dividing total annual miles driven by MPG is one easy calculation. When I track my mileage, MPG is also very easy to calculate since I just divide my miles driven since the last fill-up by the number of gallons required to fill the tank to get MPG without then needing to convert that number to a per 100 miles base.
The bottom line is that the two numbers are just different ways of expressing the same mathematical data, so to say that one is "stupid" and the other is "more meaningful" is actually a pretty stupid statement in itself (this is directed toward the idiot cited in the article and not to any commenter posting on this thread). People who are not mathematically smart enough to figure out that an increase from 10 mpg to 20 mpg will save them more gas and more money than an increase from 35 mpg to 50 mpg would will be just as confused and inept at figuring out whether an improvement from 10 to 5 gphm is better or worse than an improvement from 2.857 to 2.000 gphm. (It really doesn't matter how easy it is to calculate when you are a mathematical idiot to begin with.)
Either number can be meaningful and helpful for consumer information and for performance metrics (which should be entirely left to the marketplace rather than dictated by government). Since a standard has already been established in the marketplace of measuring the car's fuel efficiency in terms of miles per gallon, changing this measure would be counterproductive (and costly) in the short term and would probably have negligible -- if any -- benefit in the long term. If the marketplace decides -- response to demand in the marketplace -- to change the way fuel efficiency is expressed, then that is fine. But if some bed-wetting anti-consumerism bureaucrat decides that the way we express fuel efficiency here is "stupid" and it would be better if we were more like the Europeans, and as a result regulations are imposed requiring that auto manufacturers and dealers have to revise the way the numbers are calculated and displayed on the stickers (and I guess that means all those on-board computers will need to be reprogrammed so they comply with the new government edict) all that is accomplished is that consumers are given a DIFFERNT piece of inaccurate information that most of them won't know what to do with in the first place, but we will have successfully increased costs for everybody. After all, if we can spread more costs around for everybody then that's better, isn't it.
For mpg one's a difference of 10 and the other 15. Yet 15 isn't as much of an improvement -- counter-intuitive. For gphm one's an improvement of 5 and the other is an improvement of less than one. Wouldn't you know it, the larger difference is actually a bigger improvement.
Either number can be meaningful and helpful for consumer information and for performance metrics (which should be entirely left to the marketplace rather than dictated by government).
But only one clearly shows relative differences that directly reflect how much the gas price will hit your pockebook. And that mpg label is already dictated by government.
Because that's what the measurements are. Miles per gallon is a measurement of distance -- how many miles can I go per gallon of gas. Gallons per 100 miles is a measure of consumption -- how many gallons do I use per 100 miles of travel. Consumption directly equates to cost.
But my larger point is that one type of measure will predominate in the USA and another in Europe, because Americans and Europeans think about things like consumption differently.
Having lived in Europe I can tell you we think the same way about this. Every average person who drives watches gas prices just like here, web sites report the gas prices around town just like here. However, due to the price of gas over there mileage is likely to be a larger factor for the average person, so maybe it is more important that it be expressed more intuitively.
We do a lot of things backwards here. There is no pride to be had in that. Five decades after the space age began we still use a measurement derived from how long some fool king's foot was 900 years ago (the foot), a measurement defined as eight times the length of a furrow in an acre-sized field in ninth-century England (a mile), and a measurement defined as one eighth the volume of 56 pounds of wheat (the gallon), the pound itself being the weight (not mass, but average weight at sea level on Earth) of 7,000 grains of a cereal seed. Don't get me started on the rest of our measurements like link, rod, dram, jigger, hogshead, peck and pennyweight. I can't tell you exactly what any of those are, and probably only some trivia freak knows all of our measurements.
Our system -- wait, I don't want to lay claim to it. The antiquated, bastardized British/French system we use IS stupid.
Knowing only what a gram, meter, degree and liter are, and knowing the basic multiplier prefixes like milli and kilo, I can understand any physical measurement in metric. In fact, they all come together at 1 cubic centimeter of water at 0 degrees celsius having a mass of one gram and defining one milliliter of volume. So questions such as "how much does a gallon of water weigh?" are senseless (FYI I looked it up, 8.3454 pounds). One milliliter of water having the mass of one gram, one liter of water will have a mass of one kilogram. Simple.
And you can fit it in a cube 10cm on a side (one decimeter). What's the size of a gallon? I don't know. Looking it up, I see a cubic foot is 7.48 gallons. Too much math to get so basic an answer. Flow is measured cubic feet per minute, so to get a gallon idea I have to look up 7.48 and multiply, to get weight look-up and multiply again. Metric flow is measured in cubic meters, so to get liters is easy by adding the zeroes, 10x10x10 decimeters = 1,000 liters (= 1,000 kilograms = one metric ton).
Ah, I miss metrics. Here I only get it with my medication, half my tools and large bottles of soda. It doesn't have much advantage when used so sporadically.
I don’t think the average American pays attention to the price of gas unless it get’s really high. For the most part we get gas based on need and convenience, while there are people that worry about price most don’t worry about it. I see it all the time at an intersection near my house, on the NW corner is a Circle K with gas, no the SW corner is a Shell, the Circle K consistently runs a nickle higher, yet the pumps are just as regularly occupied as the cheaper ones across the street. I’m guess most of them it’s for convenience of traffic, if you’re continuing on westbound or northbound (though they’re both kind of hairy for north) the Circle K is much easier to get out of on path.
My favorite place to get gas is my favorite because of ease of traffic also, it’s on my normal path home from work and the gym, it’s an easy right turn in, and an easy right turn back onto my normal path. I can’t even see the price sign from my normal drive, but it really doesn’t matter because I’ve decided to get gas there on that trip probably before I even started the car. I filled up yesterday and don’t even know how much it cost, I glanced at the prices when I pulled in but it didn’t matter enough for me to remember 17 hours later. I do remember thinking I cut it pretty close when I saw the quantity of gas put in was 11.999 gallons.
Which is all part of why MPG works better for Americans. While truthfully the two options are the exact same calculation MPG solves to what Americans care about: how far can I go with what’s in the tank. While GPM(x100) solves for what some people THINK we should care about: how much gas am I burning and it’s subsequent costs. Maybe Europeans care about that, but Americans don’t, and every car that pulls into a more expensive gas station because it’s more convenient proves that.
It is a question of what you use the information for.
Now, if you want to browbeat people about how much fuel they use, and the reletive merits of SUVs vs Priuses, then the Gal/100Mile figure makes more sense.
However, if you are interested in everyday calculating of how much things are going to cost you on a daily basis, MPG is the way to go.
I would suggest that when people are using MPG information for vehicle seleciton, almost always they are comparing vehicles in the same class. One SUV might get 16 MPG and the other 18 MPG. For this type of discrimination, the MPG figure is perfectly fine, and it is well understood.
But if I am trying to decide whether to drive the Hummer, the Smart Car or the Prius to carry my six children and a dog, then, perhaps, the Gallon/100 mile figure might be more convenient. I am not often faced with that choice, however.
But, at the end of the day, it is a matter of attitude. Is your question defined by how many miles you drive, or by how much fuel you have? If it is the former, the milage is the independent factor. If it is the latter, the fuel quanitity is the independent factor.
Back in the third grade, I was taught that you always put the independent factor in the numerator and the dependant factor in denominator.
So if you control how many miles you drive, you would put miles in the numerator and gallons consumed in the denominator, or MPG.
However, if your activities are constrained by fuel available, that would be the independent variable, and you would put that in the numerator and the miles traveled in the denominator, or Gallons per Mile (or 100 miles, so we can deal with intergers).
So, it’s all in how you view the problem. Just like some people see the glass as half empty and some as half full, people approach problems from opposite directions, sometimes. I would submit that in the US, where people feel generally free to do as they please, travel vast distances, and consume whatever they can afford, it is only natural that Miles Traveled would be the independent factor. I would also submit the in Europe, where fuel is much more expensive, travel is much more restricted, and rationing is a more recent memory, it makes perfect sense to treat Fuel Available as the independent factor. It is the two sides of the same problem.
It seems to me that the US National Research Council (whatever the Hell that is) wnats people to change their attitudes about driving and to start looking at fuel as being a limited resource, that may be rationed or priced out of affordability for the common man. So they seek to change attitudes by changing the way information is presented.
I object to their agenda, because I still think that fuel is limited only by how much I choose to buy, and that how much I drive and consume is nobody’s business but my own. When I drive, my greater concern is miles traveled, and time expended. Fuel consumption still falls way down on the list. I suspect that is true of a lot of people in the US, and I hope it remains so.
We’re not Europeans. We don’t think like Europeans or value the same things they value. We don’t want to be like the Europeans. We are not “stupid” because we cherish freedom and the wide open road. Europeans are not “smart” because they view their freedoms as limited by fuel or cost.
The other reason the US National Research Council (Whatever the Hell That Is) may be interested in changing the to a consumption figure is the way Corporate Average Fuel Economy is calculated.
Suppose a corporation offers a fleet comprised of four models, one getting 10 miles per gallon, one getting 20 miles per gallon, one getting 30 miles per gallon and one getting 40 miles per gallon.
10 MPG = 10.0 gphm
20 MPG = 5.0 gphm
30 MPG = 3.33 gphm
40 MPG = 2.5 gphm
For the sake of argument, lets assume that Congress (in their infinite wisdom) decides that the Corporate Average Fuel Economy should be modeled on the 30 MPG vehicle.
Now, if we are averaging by MPG, we can have One 10 MPG car, Two 20 MPG cars, Four 30 MPG cars and Three 40 MPG cars to average out to 30 MPG.
(1x10 + 2x20 + 4x30 +3x40)/10 = 30
But, if we are averaging by gphm, if we have only One 10 MPG car and One 20 MPG car, we can only have One 33 MPG car and must have SEVEN 40 MPG cars to average 3.33 gphm.
(1x10 + 1x5 + 1x3.33 + 7x2.5)/10 = 3.33
So, you can see how using the gphm figure would force the car companies to manufacture and subsidize a far higher percentage of high milage cars to “pay” for each gas guzzler produced. It makes the whip hand of big government “whippier” an the jack-boot “bootier”...
Apparently this suits the US National Research Council (Whatever the Hell That Is), just fine. I do not share this view. The heavy hand of government is already quite heavy enough, thank you very much...
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.