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 ...
mile -> IS a distance
mile/gallon IS A FORM OF DISTANCE/Gallon
oy vey!
“If they were going to make a change I’d say they should add tank size and miles per tank. That’s really how the consumer interacts with their gas tank...”
Exactly. I do some driving in Namibia where gas stations can be widely separated and, in some of the areas where I travel, if you run out of gas, you may be well and truly screwed. When I fill up I reset the truck odometer - I really don’t care what the fuel gauge says, as long as it’s not doing something weird (one time I broke the line between the two gas tanks and lost a bunch of fuel, but that’s another story - and don’t get me started on flat tires). Anyway, if I’m randomly traveling and get up to about the 700km mark, I get out the map - I need to know how far I’ve gone and how far it is to someplace with fuel - with a BIG margin of error. Actual cost for gas is about the same as the US, but with the exchange rate a fill-up (150 liters) runs about 900 Namibian Dollars - makes you swallow hard to see the numbers rolling by on the pump.
Well I’m not going to a dealership any time soon (like 5 years at least, my car is barely broken in). But if that’s what they’re putting on there it shows I’m right, with gas prices not $4, and me not driving 15,000 miles a year it forces me to do all kinds of extra math to get really no data.
And then the other stuff you’re wanting to add in also stuff that varies dramatically. Cost of basic maintenance where? At the dealer who tends to charge quite a bit? At the econolube places that list cheap but always try to scam $100 out of you for unneeded repairs? Insurance for a driver of what gender and age and driving record? And would it at Bob’s insurance company for reprobates or USAA? Depending on the state even registration get’s hairy, AZ registration is based on KBB value for the car, easy to list for the first year but after that who can say.
The problem with all the stuff we already put on stickers, and the more people would want them to, is it’s all based on assumptions, mostly assumptions that aren’t listed and even if listed unwinding those assumptions to relate to the life of the potential buyer could involve some pretty tricky math.
They are not as easily calculated.
MPG, take the mileage from your trip odometer and divide by how much gas you put in the tank.
L/100KM, take your MPG and then divide by 235.2
If you enough money for 5 gallons of fuel how far can you go? MPGx5, L/100KM who knows.
I recently took a new Dodge with the Cummins diesel on a
500 mile run. Got about 18mpg at 70-75 and it was a pleasure
to drive.
I'll believe the Bible. You get two measurements of 10 cubits and 30 cubits. According to the rules of math it would be inappropriate to assume precision in measurement not explicitly stated; thus, both measurements have only one significant figure. Based on that we can only reverse-calculate pi to one significant figure: 3.
So the Bible says pi is 3, to one significant figure. That is absolutely correct.
You must have had the same engineering prof I did.
How about we mandate a sticker on all the 10 ethanol pumps, “Using this fuel will reduce your milage by 15%”
That’s true, but not really the point when you are out shopping for a new car.
When you go shopping for a new car (if you are smart) you have a idea of what kind of money you can afford to pay monthly for a car.
In that figure you had better include more than just the price of gas.
That is why I think it would be convenient to include generic figures for maintenance, insurance and registration. All of these thing contribute to the annual cost of owning a car.
>By the way, the square root of 2 is now rounded to 1 and the square root of 3 is now rounded to 2. Easier to work with and trigonometry is a whole lot simpler.
Damn, now I wish my college trig course allowed that... it would indeed have been a *wholw* lot easier.
;)
"Do you save more gasoline by going from 10 to 20 mpg, or going from 33 to 50 mpg?"Most drivers, [the greenie weenies claim], would pick the second option.
They fail to credit their colleagues in public education for such crashing innumeracy.
Of course, maybe there's a reason pilots use gallons per hour and not hours or miles per gallon. Perhaps it has to do with the relative inconvenience of running out.
Or if a person sees himself rationing his own money.
But rationing one's money is so European. Spend! Spend! Spend!
I remember in my old car which got about 220 city miles and 250 highway on a tank driving to San Francisco on I5, seeing a sign that said the next gas station was the last one for like 240 miles and hoping for nice smooth freeway traffic all the way. Honestly I don’t think I ever knew the MPG of that car, I could have done the math but it didn’t matter, I knew once the trip odometer (my “real” gas gauge just like for you) clicked to 200 I thought about my plans for the next couple of days to decide when I was getting gas.
But a yearly ownership cost number would be a better bases for comparison shopping.
I'll take that to mean if you had enough money for 5 liters of fuel how far can you go so you're not adding the conversion to metric. If my car gets 10 l/100 km, it's obvious I can go 50 km.
But that's not what the article is about. It's about people trying to compare the efficiency of cars when shopping. As I've shown, a volume/distance measurement is better for that purpose than distance/volume.
I do that, too.
A linear gas gauge, it seems, is an unsolved problem in automotive engineering. They always seem to speed up noticeably as they approach empty.
I used to bomb around Kenya with a bitchy girlfriend in a an old Renault 4 that had no gas guage. You would fill the tank and calculate when the next fill-up would be needed and write that number on a pad and keep that pad in the bin under the dash to figure out when you needed to fill up again. Or you could just run into the reserve and turn the stopcock down and you knew you had about 20 miles to go. Not far enough, if you’re out in the bush.
Anyway, once I screwed up and ran the thing out of gas in the middle of a herd of cape buffalo. I reached down to turn the stopcock, and my heart fell to my feet when I found it was already pointing down.
Well, the girlfriend really started letting me have it at this point. Just thinking about it pisses me off, even to this day. After about five minutes of that, I said “to Hell with this”, grabbed the gas can and got out of the car to take my chances with the buffalo. I figured getting trampled to death was better than listening to that...
They’re kinda like bees, right?!? You don’t bother them and they won’t bother you...
So, you buy as much gas as you can with the money in your pocket, then pick a destination you can reach. "Hey! I found 20 bucks on the floorboard! Lets go to Albuquerque!"
On the other hand, if you travel 100 miles round trip for work, you know exactly how much gas you need if you know gallons/100miles.
But so much of that information is best sought elsewhere. When I was prepping for my most recent buy and I’d narrowed down my selection I called my insurance company to find out how my insurance would change. And took it to my mechanic for a once over their opinion on durability and how often they figured they’d see me. The manufacturer/ dealership doesn’t know my insurance rates or how my driving habits effect maintenance, so any attempt by them to figure that into a cost of ownership listing on the sticker is just them making up numbers.
Exprees the sticker number in “Polution Units per Lifecycle” - the greens will have a stroke when they discover the Prius is worse that a Suburban...
I don’t think the concept of significant figures was around at the time this was written. And you’d better hope atheists designed the airplanes you fly in.
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