Slashdot Mirror
2 In 3 Misunderstand Gas Mileage; Here's Why
thecarchik sends in this piece, which was published last March but remains timely: "OK, so here's a little test: Which saves more gasoline, going from 10 to 20 mpg, or going from 33 to 50 mpg? If you're like most Americans, you picked the second one. But, in fact, that's exactly backwards. Over any given mileage, replacing a 10-mpg vehicle with one that gets 20 mpg saves five times the gasoline that replacing a 33-mpg vehicle with one that gets 50 does. Last summer, Duke University's Fuqua School of Business released a study that shows how much damage comes from using MPG instead of consumption to measure how green a car is. Management professors Richard Larick and Jack Soll's experiments proved that consumers thought fuel consumption was cut at an even rate as mileage increased."
Yup, the average person is mathematically still an infant (or has forgotten all they learned and reverted back to infancy).
What they need to start doing is standardizing how they mark vehicles fuel consumption. Here in Australia, they label most electric appliances with a sticker in the shops that shows you just how much energy it consumed compared to other similar alliances. It's not perfect, but it's a start in the right direction, and it has been running for a long time.
Perhaps they could start doing something like this with cars?
Moved to http://soylentnews.org/. You are invited to join us too!
Not to feed the trolls, but ... Screw that, I'll just check the box.
I also want to point out that the ethanol often comes from corn, which we could be using to feed more of the world's poor, or to convert into biofuels to free our diesel engines (which run better than gasoline in the long haul anyways) from petroleum products, and we could use more of the components from the corn.
Of course, putting out a stranglehold demand on corn causes companies like Monsanto to create more and craftier GM corn, causing certain monopolies to become larger still.
GM crops, just one more poison killing the human race.
The correct answer is to subtract the inverse of the numbers:
1/10 - 1/20 = 0.10 - 0.05 = Saves 0.05 gallons per mile
1/33 - 1/50 = 0.03 - 0.02 = Saves 0.01 gallons per mile
While working Cash For Clunkers in the United States, a lot of people were griping about how (people who got some new pickup truck with a 2mpg increase over told one) were getting the same credit as people who replaced their old car with a new one that gets like 10 or 15mpg more. Maybe if they had known about this, they'd understand.
Of course, when cars fly, km won't be relevant because the international standard for aviation is nautical miles and velocity in knots.
--Jim (me)
a typical vehicle goes 300 miles on a tank of gas.
What? You should be able to drive a typical vehicle about 1000km (600 miles) on one tank. I've driven a Golf IV 1100km with two people and packed to the roof on one tank of diesel (less than 5l/100km (ca. 50mpg)).
(Also check your example numbers.)
So let's use English units (even though England doesn't even use them anymore!)
There are 128 fluid ounces (oz) in a gallon. So oz/mile (let's call it OPM) is equivalent to gallons/128 miles.
This also happens to be about half the European value. (5 L/100km == 2.72 OPM == 47 MPG)
(T>t && O(n)--) == sqrt(666)
Everybody I know who isn't poor drives their cars into the ground.
The few people I know who always have to have a new car are up to their eyeballs in debt.
3 / 2
= 3 * 0.00067 cents / 2 * 0.00067 cents
= 0.002 cents / 0.00133 cents
= 0.002 dollars / 0.00133 cents
= 150
Gee, that wasn't hard, was it?
For whatever reason, we don't seem to use a metric equivalent very often here in Australia, though what we use is similar to your GPM.
Virtually every vehicle is measured in litres per 100km. For example, when I bought my car brand new back in 2006, it was rated at 5.5 litres per 100km of city driving, 4.4 litres highway driving (I was supposed to get 900km on a 40 litre tank, though in practice I get closer to 840km on the highway.)
Growing up, we used to drive from Tamworth to Canberra (~850km, depending on your route) to visit relatives, and petrol stations were very few and far between. And if it was after 8pm, they were all closed, which was hell for our thirsty 1976 Cressida.
Perhaps you have no idea what they do when you're not watching them on the particular road you saw them on. Perhaps you don't see them when they're pulling a trailer, or hauling a soccer team around, or carrying three kayaks, etc. I guess you'd rather that person have a second vehicle manufactured for him, which he can separately maintain, insure, and store somewhere. That's super efficient.
Don't disappoint your bird dog. Go to the range.
Now in a general sense, should corn be used to produce ethanol? No, and that's a result of the lobby that you mentioned.
There IS a benefit to using corn (for now). If we encourage ethanol use, then an infrastructure gets built up which can handle ethanol. When the cellulosic ethanol starts to become more widely available, that can replace the corn-based, and the infrastructure will be in place. It is a bet, to be sure, but seems to be much more realistic than the hydrogen proposals out there. Bio-diesel is also a strong contender, but there's already a infrastructure in place for that, and you still need a fuel for the cold-weather states.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
The depth of a joke that EnergyStar is was put in stark relief when the GAO (through a fake company set up for this very purpose) managed to get an EnergyStar label for a gasoline-powered alarm clock.
The
I never really managed to wrap my mind around the concept of MPG either. Yes, I'm European.
I wonder why it's defined that way in the US. It sure sounds more positive. I mean, you "get" a certain amount of miles out of a gallon of gas instead of "needing" a certain amount of gas to go 100km. Still I think it's easier to compare lp100km rather than mpg. It's trivial to calculate how much a kilometer costs me. Not so with mpg.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
The designer wants the smallest tank he can sell in the market, because it occupies precious volume and has weight. It's not just the weight of the tank wall itself, but the weight of the entire volume of car structure that surrounds and protects the tank. If you simply expanded the volume the cheapest way, you would lose the cargo volume of the vehicle. Increasing the car body size to compensate will add a lot of metal and glass. Also, you have to engineer the tank and support structures to handle its weight when full, so that also increases the weight of the supports beyond merely scaling by surface area...
Their numbers are under controlled circumstances. They vary by driver, conditions, and modifications.
My car, a 2000 Pontiac Firebird TransAm WS/6 with a 6 speed manual, is rated for 16/25.
In my own long term testing, I get 25mpg at 55mph, which increases to 26mpg at 65mph, 27mpg at 75mph, and 28mpg at 90mph. I've never felt comfortable doing long term tests over 90mph. :) All of the highway speeds are the normal cruising speed during the test. It does not include the acceleration and deceleration periods, which are very similar (and insignificant) compared to the length of a test. A test was at least 3/4 tank of gas (12 gallons).
55mph = 300 miles
65mph = 312 miles
75mph = 324 miles
90mph = 336 miles
A few times, tests used the full tank (16 gallons) due to limited access to gas stations. At 55mph, I'd get 400 miles. At 90mph, I'd get 448 miles. That 48 miles is a huge difference, if I suddenly had to walk to the next gas station 30 miles away.
If the EPA number was accurate, I would have never driven a 425 mile leg of a trip, which I've done quite a few times.
Tests which involved mixed traffic or uneven terrain (i.e., mountains) are excluded from my results.
In city driving, I get about 20mpg, which I have seen fluctuate between 18mpg to 22mpg. When I do a lot of city driving, I use 20mpg to estimate my range.
In racing, my numbers are much lower, as can be expected. :)
Serious? Seriousness is well above my pay grade.
I had to cringe when you said "is underfunded and overstretched". Really this sort of organization shouldn't require any funding, and should simply use trademark rights to assert licensing terms with partners (manufactures, building contractors, etc). EnergyStar *almost* operates that way right now, given that it is a voluntary program.
UL(Underwriters Laboratories) is a private entity that required certain specific safety testing to be passed by a product before the UL logo can be placed on that product. They have a fairly narrow scope though, mainly for fire safety. But it is one of only a few testing labs recognized by various local building codes in the US as well as federal organizations such as OSHA. Testing fees are modest, and the organization is able to scale with demand.
Another example with is Snell. To use their logo on your helmet requires specific tests, the tests are fairly expensive so not all helmets are Snell certified, but part of their budget funds helmet safety research.
Why EnergyStar can't operated the same way, I do not understand. It seems like if we had an international standard (one of the positive aspects of EnergyStar) that provided oversight and certification of various testing facilities to authorize them to grant limited rights to licensed partners to claim certification would be scalable and efficient.
With an obscure government entity there are almost always problems with oversight and responsibility. When EnergyStar gets in trouble there is no CEO or politician to blame, it's all just faceless bureaucrats. In situations like these it is the media's responsibility to expose failures in a bureaucracy, but the side effect is consumer trust in the EnergyStar brand is damaged. A business operates differently when trust in a brand is important.
“Common sense is not so common.” — Voltaire
It would be best to have the MPG meter visible on the dashboard all the time as part of the speedometer. Specifically the one that shows the immediate effect of you pressing down the accelerator rather than the average usage - might be handy to have it alternate showing the value of the petrol you've just used as well - a bit like those pieces of gym equipment that shows you both the watts and the calories being used
"The hands that help are better far than lips that pray." - Robert Ingersoll (1833-1899)
"Why is the US so stubborn about adopting the International System of Units? Even the country where the "Imperial" units come from did."
That's a very good question. Does this Metrication Matters guy have any answers? If we want to metrify the US, a good first step would be to figure out why we haven't already, and not just bitch and moan about Americans being stubborn. The only other countries that haven't switched to metric are Burma and Liberia, but maybe we could compare America with countries that were slow to switch? One hypothesis that comes to mind is that America is the largest economy of the world. The products Americans use are either made by Americans, or by companies who suck it up and provide "imperial" measurements. Other countries didn't have so much economic pull, and were faced with products labeled in "foreign" measurements. So there was some incentive to switch to some single measuring system. Ways of testing this hypothesis: I think the UK used to be a much larger economy (in terms of percentage of global GDP) than it is now. When did the UK switch? If this hypothesis is right, autarkies should be less likely to switch. This might explain why Burma hasn't switched yet. When did the DPRK switch?
I'll admit that this hypothesis is probably BS, but does anybody have a better one?
In the meantime, switching to consumption rather than mileage makes a lot of sense, even if we do it using "Imperial" units instead of metric. Don't let perfection be the enemy of the better than what we have.