If a train can get 750 TMPG, what's the number for this?
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 ...
Excellent explanation. Amazes me how many people think the idea of switching is stupid — this isn’t like the metric system, the gallons/mile measurement is actually a much better comparison than miles per gallon, for the reasons you give.
MPG makes people do stupid things, like trade in a 30mpg car for a 40mpg car to “help the environment”, while deciding to keep their 12mpg truck instead of getting a 20mpg truck because it’s “not enough of an improvement”.
It’s why I laugh when people get to arguing about “how much better” some car might be than another because one gets 45mpg, and another gets 50 mpg.
There is another aspect that you didn’t directly address. Not only is a 10 to 20 mpg (100% improvement) better directly than 40 to 50 mpg (25% improvement). But all else being equal (meaning the USE of the vehicle), improving from 10 to 20 mpg is much more than 4 times better than the 40 to 50 mpg improvement.
Suppose you drive your car 10,000 miles per year. At 10 mpg, you used 1000 gallons; improving to 20mpg, you use 500 gallons, saving 500 gallons.
At 40 mpg you used 250 gallons; improving to 50mpg means you use 200 gallons. That’s only a 50 gallon savings, which means you saved 10 times as much going from 10 to 20 mpg, as you would going from 40 to 50 mpg.
It’s why hybrid trucks are a much better use of hybrid technology than the hybrid cars. Small mileage improvements make a big difference when the absolute numbers are very low.
Note that if you can improve your mileage from 10mpg to 20 mpg, you get as much savings as if you had a 20 mpg car and traded it in for an electric car charged by free electricity.
I don’t think a generic yearly figure helps anybody, because nobody knows how they relate to that figure. We might know how we relate in general to it, but not specific enough to be able to look at their figure and know what it is for us. I know my insurance is cheaper than any average the dealer might pick because my FIL was career Air Force and subsequently we get to use USAA, but I don’t know how much cheaper without calling USAA, at which point I won’t be paying any attention to dealer numbers. And if you’re working the numbers for your budget how much is what matters, so unless the prospective buyer is Mr Generic putting those numbers on the sticker won’t help him at all.
I am guessing that you were long hauling on flat interstate highways.
But that was probably the best engine GM had ever made.
A friend of mine’s dad had an Eldorado with the 500 in it. Having that car burn rubber with the front wheels was quite a sight.
His dad was a little naive to let him borrow that car.
So the question is which measure do you consider more relevant: Fuel consumption or fuel efficiency?
Fuel consumption asks "how much fuel do I have to consume to go a certain distance?" Fuel efficiency asks "how much distance can I get out of a given amount of fuel"? If I have a fixed size gas tank (as all cars do), and I want to know how far I can go on that tank of gas, then fuel efficiency -- rather than fuel consumption -- is more important to me.
Thanks. I’ve seen some of those on the road and thought they were trying for a retro of the old Chevrolet delivery vans of the early 1950’s. But anybody who buys GM and expects reliability is being MUCHO overly optimistic.
True. But what if I asked you to compare 10 to 20 mpg, vs 20 to 40 mpg?
You might say they are equal, because in both cases you double your miles per gallon.
But if we look at gallons per 100 miles, we'd see that's not the case. 10 mpg is 10 gphm. 20 mpg is 5 gphm. 40 mpg is 2.5 gphm.
So you can see that improving from 10 to 20 mpg saves you 5 gallons of gas per 100 miles driven. improving from 20 to 40 mpg only saves you 2.5 gallons per 100 miles driven.
Extra credit: How much better do you need from a 20 mpg car to save as much gasoline as you save going from 10 mpg to 20 mpg?
Answer: You can't. You'd need an electric car, because you have to improve from 20 mpg to infinite miles per gallon;
The gallons per 100 miles measurement makes it easy to see exactly how much gasoline you would save with the improvement; and since most people know how many miles they drive a year, they can quickly and easily figure out how many fewer gallons of gas they would use, which would tell them whether upgrading their car would ever pay off.
Most people assume that if they could improve their car from 50 mpg to 100 mpg, they'd pay off as quickly as, say, improving from 10 to 20 mpg. in fact, you save 1 gallon per 100 miles improving from 50 to 100 mpg. To save the same amount if you have a 10 mpg car (10 gallons per 100), you only need to go to 9 gallons per 100, which is about 11 miles per gallon.
IN other words, in terms of absolute savings, making sure your 10 mpg car is tuned up and the tires are fully inflated (gaining you around 2 mpg improvement) will save you more money each year than converting a 50 mpg car into an electric car.
I think the problem here is that people that buy a car to “help the environment” are idiots anyway, so no matter how you express the information, whether as MPG or GPM, they’re probably still going to make a stupid decision.
If I woke up in the morning and decided today was the day to improve the fuel efficiency of the household “fleet” I’d figure out which vehicle had the lowest MPG (or GPM doesn’t matter because it’s the same data with the math worked the other direction), decide if I wanted to still have a vehicle in that category, and replace it with something that has better MPG possibly in that category. Because I already know that a 4 or 5 MPG change (which if you remain in category is what you’ll probably be able to easily achieve) is more effective when added to a small number than a big number, and I don’t need it to be GPM to figure that out, it’s grade school math. And anybody that can’t work out that math on their own without reversing the equation is going to wind up just as confused by GPM as they are by MPG and will continue to make silly decisions.
Plus, what difference does it make what you use as a measuring method.I simply fill up my vehicles when the gas gage says it's time.
Actually, that is backwards.
If you have 1 gallon of fuel, and want to know how far you can go, miles per gallon easily tells you; it is how far you can go on 1 gallon of fuel.
If fuel is unlimited, and the important thing to you is how far you drive (and that IS the important thing, nobody decides to drive “1 gallon’s worth”, people want to get from point A to point B, which is X miles), then Gallons/100 miles is the important measure. You want to go 100 miles, gallons/100 miles tells you how many gallons of gasoline you should get.
As shown, "efficiency" as you call it, the distance/volume method, leads to confusion. If it didn't, that trick question test wouldn't have been floating around for so long, with so many people getting it wrong.
You can't use mpg to compare the efficiency of a two seater versus a minivan.
Exactly right. But I'm usually more interested in how far I can go than in how much I use. So, I'll stick with MPG. F U, greenies!
Also, calculations using MPG are easier to do in your head than with GPM. Google says it's 2500 miles from here to Flagstaff. If my car gets 25mpg, then I know instantly the drive will take 100 gallons and cost $250 to $300 in fuel. If I instead start with the equivalent but pedantic greeniac 0.04gpm metric, I'd probably flip it my head first, instead of using it directly. Otherwise, I'd probably go back to Google.
This is correct. The proper measurement should be in Ton Miles Per Gallon and not Miles Per Gallon. The true measure of cost and efficiency must take into account how much mass is moved as well as the distance it is moved.
My guess is that taxation is the reason behind recording gallons used per one hundred miles. Remember, the more miles you go on a gallon of fuel means less taxes collected for the distance you traveled. The automobile instruments cannot recall the MPG measurement. However, the odometer records miles traveled and a record of the amount of fuel you purchased is available.
Which is more fuel efficient; a vehicle that can move two people forty miles on one gallon of fuel (40 MPG) or a vehicle that can move ten people forty miles on four gallons of fuel (10 MPG)?
An automobile can deliver 25 to 50 gross ton miles per gallon.
A jet airliner can deliver 60 to 65 gross ton miles per gallon.
A bus can deliver 110 to 120 gross ton miles per gallon.
A large truck can deliver 120 to 200 gross ton miles per gallon.
A train can deliver 750 gross ton miles per gallon.
Which is more fuel efficient; a vehicle that can move two people forty miles on one gallon of fuel (40 MPG) or a vehicle that can move ten people forty miles on four gallons of fuel (10 MPG)?
Which is more efficient; a vehicle that can move ten people forty miles on four gallons of fuel (10 MPG) or a truck that can move thirty tons forty miles on eight gallons of fuel (5 MPG)?
I knew this farmer who found a cheetah cub that was orphaned after its mother was killed in a brushfire. He took it home and cared for it and it got pretty tame and just kind of wandered around his land. We were camped on his property and into our camp strolls the cheetah - I don’t think one of the students with me got out of the truck for the next month.
So, the question is, what do you want to know?
If you know that you are going to drive a certain amount in a year, say 10,000 miles, you can figure out how many gallons of gas you will use by simply dividing 10,000 by the MPG. All very straighforward.
But if you are trying to compare, apples to apples, different vehicles, then consumption figures make more sense.
One question is, “How much is this car gonna cost me?”, and the other is “Which of these cars is gonna cost me less?”
If your concern is affording the vehicle, the first question is pertinent. If you are trying to reduce your consumption for some external reason, unrelated to absolute cost, then the second one is more relevant.
I would submit, that for most Americans, the former question is the one they worry about. They want to figure out how much it will cost and then weigh that cost against their desire, and come to a decision. This reflects the American attitude that the budget does not define the decision, but rather desire.
But for most Europeans, it seems to me, the budget is the dominant factor. Under such constraints, using the consumption figure makes perfect sense, and it would be inconvenient to do things any other way.
So, it is not the way Americans express auto milage that the US National Research Council has a problem with, but rather the way Americans feel about consumption in general. The “Make more, spend more” attitude of Americans infuriates them, because it does not respect their certainty that supply is limited, so we must all limit our desires.
The argument here is whether people can discern if 4G/100mi vs 4.54G/100mi is a better indication of improvement over 25MPG vs 22MPG. The answer is no because you divide one over the other to get a ratio or percentage of improvement.
It is a moot point for the same reason Americans still use SAE for tools and the British still use stones for weight.
If a train can get 750 TMPG, what's the number for this?
Was his name "Wales", by any chance?
Here is an example of how I see using such a generic number.
I am looking for a new car. All of the cars I am looking at have about a $500 per month payment.
I have figure out my budget so that I $4000 in my budget to operate my car while driving 15,000 miles per year (after making the payment). Below would be the estimates provided of the cars that I have been looking at as prospects.
Car A cost $3500 to operate for 15,000 miles per year.
Car B cost $3200 to operate for 15,000 miles per year.
Car C cost $3700 to operate for 15,000 miles per year.
Car D cost $3900 to operate for 15,000 miles per year. .
Car E cost $4500 to operate for 15,000 miles per year.
Car F cost $4200 to operate for 15,000 miles per year.
I would eliminate cars E and F because they are outside my budget. I would probably eliminate D because it is a little close for comfort. I would then call my insurance agent and get detailed figures for Cars A, B and C from my insurance agent. I would also check out Consumer Reports for reliability history.
If I find that my insurance rates are substantially lower than expected making the other cars more affordable I may reconsider them. I just see this figure I suggest as a useful tool for ball park comparison.
You have to divide, which is trickier when the numbers don't fit so cleanly, like you get 18 mpg and you're going 2,500 miles. You might want a calculator. We would probably use gallons per hundred miles. I first have to divide, but since it's by 100 I just ignore two zeroes, so it doesn't add much for complexity. Then I multiply. So 2500 * 4 = 100. Or on the more complex case, 2500 * 6 = 150 gallons. Both methods are effectively one operation for in-your-head math, only multiplication is easier than division.
What's really intresting there is that although we only lost about 7 mpg going from 25 to 18 mpg, it resulted in a 50% increase in fuel consumption (approximately, the conversion from mpg to gal/100m was rounded). We only lost about 1/4 of our mileage, so what happened? Easy if you use the other system, because that would be 4 vs. 6 gal/100m, obviously 50% more out of your wallet just from looking at the numbers.
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