fuel mileage considerations

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I happened to read this article the other day on DiscoveryNews about MPG vs Litres per 100km.




Actual fuel consumed for every 100 miles or Km vs a theoretical mpg rating.

(With that said, recent tank, BJ70, stock 3b,411's 255's= 10L per 100Km.:grinpimp:)



Miles-Per-Gallon Is Just Stupid. No, Really, It Is. - Green Car Reports



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 2010 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% 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...) 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. 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.

"More than a year ago, we wrote an article pointing out the flaws in the U.S. practice of measuring a car's gasoline use with the familiar miles-per-gallon (MPG) measure.

Now, no less a body than the august National Research Council has agreed with us.

As it noted in a pre-publication summary released by the National Academy of Sciences:

Fuel economy data cause consumers to undervalue small increases (1-4 mpg) in fuel economy for vehicles in the 15-30 mpg range.

Display consumption as well as MPG

Its panel strongly urged that the information should be displayed to consumers as fuel consumed (volume of fuel per 100 miles, for example) alongside the traditional MPG measure, which is only really used in North America.

Everywhere else, car buyers assess and compare consumption, which correlates directly to their fuel costs (as well as tailpipe emissions of greenhouse gases, predominantly carbon dioxide).

So what, exactly, is the problem with good old American miles per gallon? We laid it all out more than a year ago in an article entitled Miles Per Gallon Is Just Stupid; No, Really, It Is.

It's not linear


To illustrate the problem, just answer this question: Do you save more gasoline by going from 10 to 20 mpg, or going from 33 to 50 mpg?

Most Americans pick the second choice. But that's wrong. No matter how many miles you drive, swapping out a car that gets 10 mpg for a 20-mpg version will save you five times the amount of gasoline that going from 33 to 50 mpg will. Five times!

The problem is that the MPG scale isn't linear. A 10-mpg improvement saves vastly different amounts of gasoline, depending where on the scale it falls. But fuel consumption (gallons used to go a set distance) is linear. Halve that number, use half the gasoline.

And if you still don't believe us, read the entire original article--which caused, ummmm, quite a lot of controversy when we first published it, and continues to generate readership and interest.

Sorry, folks. Math is math. Even if, to quote Barbie, "Math is hard!"
 
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as Grg asked, this thread is for fuel mileage considerations.
many time we read about how winter fuel really affect fuel mileage but is that the only consideration?
we also read about gearing, tire size, etc etc affecting fuel mileage, some say the right gearing will compensate for taler tires and will bring the fuel mileage back to stock, is this the case.

discussion is expected.

here is my observations over 30 years of driving different Toyota diesel Land Cruisers but most apply to all engine fuel mileage returns:

things that affect fuel mileage:
Summer:
speed:
it seems for every 5 km increase in speed = 2 mpg lost in MPG
head wind:
even a gentle head wind will affect fuel mileage.
AC running:
increase load on engine, lower fuel mileage.
terrain:
even a gradual increase in elevation over a long distance (think Sask and Manitoba) will affect fuel economy similar or even worse than short steep hills.
heading east from Calgary towards Kenora you will see an increase in fuel mileage with no change in driving habits due to elevation drop.
build of the truck:
larger tires
wider tires
gearing
roof racks
custom bumpers
all will affect final fuel mileage.

winter:
longer warm up idling:
no MPG but in reality lost MPG.
snow and ice:
reduce traction which must be over come with tire rotation for forward motion. deeper the snow the worse the fuel mileage but even a skiff of snow on the road will increase fuel mileage.
cold temps:
reduce vicosity of diff/tranny/tcase fulids as well as engine oil causing increase load on the engine which in turn relates to poor MPG
harder tires which reduce traction which increase fuel consumption
leaving vehicle running while going into store or house

Contrary to popular belief it is owner practice that increase fuel consumption in the winter more than "winter fuel".
 
Sorry Wayne, I know you started the thread but "seapotato's" post is chronologically before yours.
 
really?
no biggie to me either way... his is a great post.

Sorry Wayne, I know you started the thread but "seapotato's" post is chronologically before yours.
 
I can't change it either way. The system does it chronologically.

Back to regular programming...


... and how we can give less money to OPEC!!!
 
Wayne, the best fuel economy I ever got with the Patrol was a winter trip from Abby to Trail (about 650 kms). Temp in Abby was just below 0C when I left and temp at destination was about -20C. Road conditions were a mixture of hard pack and fresh snow over hard pack. Tires were my studded Nokians - so my overall speed on the GPS was averaging around 93 kms/hr. That is pretty fast on Hwy 3 given the grades and corners. I think those tires had a lot to do with the fuel economy. On top of the Blueberry Paulson, I was able to cruise along on the fresh snow over hard pack at between 100 - 110 kms/hr. Also, fresh injectors and a rebuilt IP helped too.

The next thing I will do (maybe this week) is to blank off the EGR on both Patrols to see if that increase fuel economy.
 
The next thing I will do (maybe this week) is to blank off the EGR on both Patrols to see if that increase fuel economy.

John, how do you think that will help? I'd think that the exhaust gas would be a little more "combustible" than simple clean air?
 
Speed: seems to be one of the biggest ones. Keep it to 90-95kmph to get the best returns.

I have been full synth in my BJ74 for 4 years. I can tell as soon as winter fuel is at the pumps. My mileage per tank goes down. And we don't get real cold here. I would think conversely that one drives more gentle in the winter when there is snow on the ground, so there would be less pedal=more efficiency. That does not seem the case. I think less BTU's in winter diesel speak more to the heart of the matter, even with increased idle time (warm up), thicker fluids, resistance to move, etc.

gb
 
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I would say engine speed is almost more critical even than actual vehicle speed. The 3B likes to run at 2000 - 2200 rpm and gets thirsty when you want to go faster.

I also think that the stock tires do give better mileage than the AT's or MT's we all like to run though I have no hard data to back that up.
 
Speed: seems to be one of the biggest ones. Keep it to 90-95kmph to get the best returns.

gb

I have noticed this, and my recent trip to Sheridan lake was no exception. At one point, I maintained a speed of between 60-65 MPH, and my consumption was 13.8L/100 kms. On the way back, I was in a bit more of a rush (fishing was lousy, lol), and increasing my average speed slightly to 70-75 MPH resulted in consumption of 15L/100 kms.

Same load, same route...gear for myself and towing my 1436L jon boat on a trailer.
 
hummm new injextors and rebuilt pump... might have a lot to do with it. increased elevation from Abby to Trail would not be conductive to imptoved fuel mileage. wouldn't you agree?
Wayne, the best fuel economy I ever got with the Patrol was a winter trip from Abby to Trail (about 650 kms). Temp in Abby was just below 0C when I left and temp at destination was about -20C. Road conditions were a mixture of hard pack and fresh snow over hard pack. Tires were my studded Nokians - so my overall speed on the GPS was averaging around 93 kms/hr. That is pretty fast on Hwy 3 given the grades and corners. I think those tires had a lot to do with the fuel economy. On top of the Blueberry Paulson, I was able to cruise along on the fresh snow over hard pack at between 100 - 110 kms/hr. Also, fresh injectors and a rebuilt IP helped too.

The next thing I will do (maybe this week) is to blank off the EGR on both Patrols to see if that increase fuel economy.
 
hummm new injextors and rebuilt pump... might have a lot to do with it. increased elevation from Abby to Trail would not be conductive to imptoved fuel mileage. wouldn't you agree?

Yes, nothing about that highway is conductive to improved fuel economy. It is a lot of up and down and corners everywhere. One would think I would have gotten my best economy on the PG trip (a couple weeks later) which has fewer mountain passes and tends to be a lot straighter up on the plateau. That trip I only got just over 10L/100kms. Perhaps that was because of the relatively straight highway from Clinton to PG. I am usually traveling at about 110 on that section of road.

I've the injectors Paul rebuilt for me to put in. He increased the breaking pressure by 50 psi over spec. He says that will give better fuel combustion. We'll see if it will impact the fuel economy. He couldn't tell because when he did his, he also advanced the timing and turned up the fuel a bit.
 
Cute article but they're playing number games and it's very deceptive.

Their comparison:

Person A goes from a 10mpg vehicle to a 20mpg vehicle
Person B goes from a 33mpg vehicle to a 50mpg vehicle

Over 100 miles Person A goes from 10 gallons consumed to 5 gallons consumed.
Over 100 miles Person B goes from 3 gallons to 2.
They use this to say that Person A has saved 5 times the fuel that Person B has saved. This is deceptive and I don't like it.

Person A has made more significant gains but theirs is not the correct way to look at it.

Person A has improved fuel economy by 100%
Person B has improved fuel economy by 52%

If you need to flip it around to wrap your head around it Person A has added 100% (doubled) the distance he can go on a gallon and Person B has only added 52% to the distance he can go on a gallon.

I know, I know. People are stupid and the point of the article is supposed to be that Americans need to learn to look at the amount of fuel they consume to do a given amount of work rather than the amount of work they can do with a given amount of fuel.

Either way, 15.3367 is 15.3367 no matter how you cut it......

:)
 
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I just ran back into my office to try to save myself from getting burned........and I was too slow. :)

Denis, I owe you a beer. Somewhere, some time...

I don't f up with numbers often and even when I do I don't get caught often.

I bow down to you.

Now don't mind me while I edit the crap out of my last post. Thanks for not quoting the big mistake! ;)
 
Do you guys suppose winter may have the advantage of colder air? Just wondering.
I've heard that colder air allows for more air in a given space, and that cooler air may allow more air to enter the engine, and thus maybe improve economy a slight bit.

Just curious if this is true.
 
I would say engine speed is almost more critical even than actual vehicle speed. The 3B likes to run at 2000 - 2200 rpm and gets thirsty when you want to go faster.

I also think that the stock tires do give better mileage than the AT's or MT's we all like to run though I have no hard data to back that up.

The power lost to wind resistance cubes with speed. It takes 73% more power to drive at 120km/h than 100km/h.

Matching engine rpm is still a big consideration to fuel economy (almost always lower rpm gives lower fuel consumption) but the speed you drive will far eclipse engine rpm as the biggest single factor in fuel economy.

Regarding mpg vs litres/distance. Mathematically it's exactly the same fraction just upside down.
Claiming one is useless and the other great suggests the article author can't do basic maths.

In winter our (diesel) engines run better, but the air is also denser so more power is lost to wind resistance. That's a big factor in winter fuel economy being worse. Warmup time etc takes it's toll as well.
 
Claiming one is useless and the other great suggests the article author can't do basic maths.

.





All of the formulas will work, because in the end they all are the same thing, how much fuel for a given distance.

he doesn't say one is a completely different formula, so I think his math is fine.

It's the rest of the world's math abilities he questions, and one way of using the formula shows actual fuel usage better than the other. That's all.

But, whatever, not my article, and wasn't something I'd have made a new thread about, I'd have been happy to have it deleted from the other thread as chat, so not sure why I'm bothering to defend it...


Looks like I'll be driving my bj70 to edmonton soon from vancouver island, so I guess I'll be figgering out how to get the best mileage soon enough...( dontcha hate it when buddies get married awkward distances away?)
 

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