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Why GPM should replace MPG (Some surprises here)

kenny

Super_Ideal_Rock
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Americans aren't stupid. We're just badly informed. And occasionally, stubborn.

Why else would we ignorantly cling to using miles per gallon as the way to measure how efficiently a car uses fuel?

But maybe you don't quite see the problem. 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.

Don't believe it? Here’s the math. If you replace your old 1990s SUV (10 mpg) with a new 2009 Chevrolet Tahoe Hybrid (20 mpg), over 100 miles you cut your gasoline consumption from 10 gallons to 5. That saves you five gallons.

If you swap your old Toyota Echo (33 mpg) for a new 2011 Toyota Prius (50 mpg), that only saves you one single gallon over the same distance--down from 3 to 2 gallons.

Yes, the Prius uses less gasoline overall, and that's absolutely greener. But like it or not, lots and lots and lots of Americans need large vehicles for their jobs, their families, and their lives. Short of truly punitive taxes on vehicle weight, footprint, or engine size, that won't quickly change.

In other words, we could cut our petroleum imports, reduce our carbon output, green the planet, and all act like happy bunnies if we replaced all our truly low-mileage "guzzlers" (we're thinking 1978 Chrysler Brougham or, hey, late-1990s Chevy Suburban) with vehicles that get just 20 miles per gallon.

That'd save a whole lot more actual gasoline than, say, replacing 3 percent of vehicles sold in the US with hybrids. Which is exactly what we've done over 10 years. In fact, US average mileage has pretty much stalled as vehicles have gotten larger, heavier, and better equipped.

This has led to all sorts of misconceptions, including the impact of the Corporate Average Fuel Economy (CAFE) regulations now being written. We actually think that higher gas taxes are a smarter way to let the market sort out what fuel consumption it will pay for, but we're not going there. (This time.)

So that's the problem: Americans can't accurately work out how to save the most gasoline. What's the solution? Simple. Measure fuel usage the way the entire rest of the world (including Canada) does: consumption over distance. There, it's mostly liters per 100 km. Here, it'd be gallons per 100 miles.

Do you know all this and just do the math in your head? Well, you're way ahead of the curve. (Test yourself first, though...) A few years ago, 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. Most survey respondents said going from 34 to 50 mpg saved more gasoline over 10,000 miles than did moving from 18 to 28 mpg. Their website, "The MPG Illusion," lays out the whole issue.

There are now a few moves toward putting consumption on window stickers, right next to mileage. And when both a Midwestern Republican Congressman and The New York Times agree on something, it's gotta have some merit, right?

That way, you could compare the Corolla's 3 gallons every 100 miles against the Prius's 2, calculate the extra cost, and decide if you wanted to make that Prius statement after all. For 8,000 miles a year, on $2/gallon gas, by the way, the gas will cost you $160 a year more.

But, hey, Americans are stubborn. We beat back the metric system, right? Consumption instead of mileage? Nah. Dumb idea. Never work. [sigh]

Source: http://www.greencarreports.com/news/1019426_miles-per-gallon-is-just-stupid-no-really-it-is
 
My Audi A6 got 18 mpg. It died of catastrophic transmission failure. A rebuilt transmission for an A6 where I am is about $7,500. And "syncing" sp? a new transmission with the electronics of my car never would have worked anyway. The car was all drive by wire. So 140,000 and done even though the body was like a tank and the engine would have gone probably 300,0000.

Then I got a Honda Accord 4 cyl. 24 mpg. I was very happy with the improvement in mpg.

My little beater Hyundai gets 30 mpg. I never want to have anything other than a small car again. I'm not good with math, Kenny, but I love getting 30 mpg. The new Hyundai Accent gets 40 mpg highway. A boy can dream.
 
I noticed this when I moved to Australia. I stubbornly argued that MPG was "easier to understand" than liters/100kms. :rolleyes: Asking an American standard of measure to change is all but impossible, as we found with the metric system. ;))
 
Great idea!

I think it would be easier to just add the GPM rather than replace it -- less arguement from those who don't want to have to use GPM and might be a good way for people with older cars to compare their current car to a new car.


We share one car in our house and drive about 1500 miles each month. Our current car is a crossover that gets about 16-18MPG.

Our new car will be here in just a few weeks. It will get almost double that! (and we aren't giving up any of our carrying ability... it actually can hold more!)
 
I completely agree with you Kenny, but isn't this old news? :confused: :confused: I've known about it since the first time I got my car in 2001 or something. I still don't understand why it's not more acknowledged.
 
I'm open minded about this but I don't understand why it would better. Can someone please explain it to me?

I like to know how many miles I'm going to get when I pay for a gallon. Am I wrong?

BTW, why can't we (in the US) have cars like these?

http://wheels.blogs.nytimes.com/2012/05/14/in-a-global-marketplace-toyota-and-volkswagen-make-room-for-niche-vehicles/?ref=automobiles

I LOVE this yellow Toyota. For years- forever actually, European and Japanese manufacturers haven't imported their smallest cars to the US. Even in the luxury market, there are always cars, like the A3 hatchback and a zillion others, that we can't get. I think it's so unfair.
 
I understand your mindset, Danny. I had it too. The fact is, a difference of 10 mpg is not the same all the time - the savings of going from 10 to 20 mpg is is MORE than the savings of going from 25 to 35 mpg. But the great majority of people wouldn't understand that. They think they're comparing apples to apples, but they are not.

If you express it as gallons per 100 miles, the comparisons are apples to apples. It tells you straight out how much actual FUEL IS CONSUMED, which is the entire point of these statistics. 2 gallons per 100 miles, 4.2 gallons per 100 miles, 548903 gallons per 100 miles. The distance traveled is constant, so the only variable is amount of fuel consumed. That is the crux of the information, knowing how much gas you're burning through.
 
justginger|1337264150|3197297 said:
If you express it as gallons per 100 miles, the comparisons are apples to apples.

I see! They can change it. That would be ok with me. Thanks, Kenny and justginger. I actually never even heard about this before. Very interesting.
 
I didn't know this, and I really do like the gpm suggestion. How do you think that this relates to the US love affair with SUV and SUV hybrids? Many of those have mpg in the teens.
 
Another pet peeve of my is . . . "How far can YOUR car go on a tank of gas?"
I've heard people say, "Mine car can go 500 miles on a tank, but your can only go 400 miles on a tank so I must get better MPG".

In fact this stupidity is so rampant I even saw a Dodge billboard that bragged . . . "Go from Los Angeles to San Francisco on ONE tank of gas!"
I laughed so hard I almost got into an accident!

HELLO! Some gas tanks vary! DUH!

The Ford Expedition EL's tank holds 33.5 5 gallons, which will take it 429 miles in the city.
A Toyota Prius C holds only 9.5 gallons, which will take it 503 miles in the city.
 
Thats why in canada the posted gas consumption is in Liters/100Km. My tdi uses only 6 liters/100Km in the city.
 
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