Fuel economy measurement across the globe

[Bob Blick-4]

Apropos of the "best calculator" thread, I am curious about the
different methods of measuring vehicle fuel economy across the globe.
Being from the United States I am of course ignorant of what system
anyone else uses. But I am enlightened enough to know that other people
have different ways of doing things.

Just for the record, in case anyone is curious, in the USA we measure
fuel economy in Miles per Gallon, where a mile is about 1609 meters and
a gallon is about 3.78 liters.

And I bet that in parts of the United Kingdom they also use Miles per
Gallon, but maybe those are Imperial Gallons(4.54 liters).

For sure in true metric countries they must use metric units, but I have
heard it's reversed, and "Liters per 100 Kilometers" is a typical way of
specifying fuel economy. If this is so, is this the norm?

So if you want to chime in with how you specify fuel economy and where
you live, it would be much appreciated (and the information will be used
in an upcoming open source PIC project).

Thanks!

Cheerful regards,
Bob

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[piclist-7]

It's worse than just having various types of units.

You also have to define how you measure it.  Your MPG will vary bases on
how fast you are driving.  And if you have to speed up and slow down. Or
stop.  Or idle.  Or go up and down a hill.

The US recently changed how they calculate city milage, and suddenly all
the cars now get worse city fuel economy.  Well the stated numbers go
down, the actual economy (or lack of it) has not changed.

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[Bob Blick-4]

On Wed, 9 Jul 2008 18:06:49 -0400 (EDT), piclist@... said:
> It's worse than just having various types of units.
>
> You also have to define how you measure it.  Your MPG will vary bases on
> how fast you are driving.  And if you have to speed up and slow down. Or
> stop.  Or idle.  Or go up and down a hill.

I think that part is generally understood.

But you didn't say where you live or what units you use.

> The US recently changed how they calculate city milage, and suddenly all
> the cars now get worse city fuel economy.  Well the stated numbers go
> down, the actual economy (or lack of it) has not changed.

There's a calculator(you can look at the source of the web page to see
the formula) to switch between the two, and also a link to the
measurement methods:

http://www.fueleconomy.gov/feg/ratings2008.shtml

Cheerful regards,

Bob

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[Tomás Ó hÉilidhe-2]

I'm from Ireland, and we're neither fully metric nor fully imperial
here. For the most part we tend to be metric, but you'll hear imperial
measurements, especially for measuring distances in miles, a person's
weight in stones, and a person's height in feet.

Strangely enough we use "miles per gallon" over here, even though very
few people here know what a gallon is.

I myself tend to talk about how many miles I get for a tenner (i.e.
tenner = 10 Euro), which has dropped lately because of increased fuel
cost. My Toyota Starlet gets me 69.7 miles for a tenner, while my
Peugeot 205 gets 47.

If you wanted to be SI about it then go for "metres per cubic metre" :-D

One thing about volume:  I know at least one person who tries to buy his
petrol in the morning rather than later in the day because when it's
cooler it's denser, so you get more mass for the same amount of money.
As for how denser it is, I don't know.

For me, I make sure I get more fuel by stretching out the fuel tube so
that I don't leave the petrol station with the tube still full of petrol.


piclist@... wrote:

> It's worse than just having various types of units.
>
> You also have to define how you measure it.  Your MPG will vary bases on
> how fast you are driving.  And if you have to speed up and slow down. Or
> stop.  Or idle.  Or go up and down a hill.
>
> The US recently changed how they calculate city milage, and suddenly all
> the cars now get worse city fuel economy.  Well the stated numbers go
> down, the actual economy (or lack of it) has not changed.
>
> --
> Ian Smith
> www.ian.org
>  

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[Rolf-4]

Bob Blick wrote:

> Apropos of the "best calculator" thread, I am curious about the
> different methods of measuring vehicle fuel economy across the globe.
> Being from the United States I am of course ignorant of what system
> anyone else uses. But I am enlightened enough to know that other people
> have different ways of doing things.
>
> Just for the record, in case anyone is curious, in the USA we measure
> fuel economy in Miles per Gallon, where a mile is about 1609 meters and
> a gallon is about 3.78 liters.
>
> And I bet that in parts of the United Kingdom they also use Miles per
> Gallon, but maybe those are Imperial Gallons(4.54 liters).
>
> For sure in true metric countries they must use metric units, but I have
> heard it's reversed, and "Liters per 100 Kilometers" is a typical way of
> specifying fuel economy. If this is so, is this the norm?
>
> So if you want to chime in with how you specify fuel economy and where
> you live, it would be much appreciated (and the information will be used
> in an upcoming open source PIC project).
>
> Thanks!
>
> Cheerful regards,
> Bob
>
>  

Canadians typically express in litres/100km.
South Africans typically express in litres/100km too, but also in
km/litre sometimes (at least it was done 10 years or so ago).

Just by the way, in most 'metric' places it is litre, not liter, and the
SI unit is litre as well. You may want to get that right if you are
planning to support international markets... ;-)

Rolf

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[Richard Prosser]

Bob,
Here in NZ litres/100km is the "official" measure, but km/litre is
common, and most of us oldies can still relate to mpg (the gallon
being the imperial variety). (After all we only went metric in 1976).

Richard P

2008/7/10 Rolf <learr@...>:

> Bob Blick wrote:
>> Apropos of the "best calculator" thread, I am curious about the
>> different methods of measuring vehicle fuel economy across the globe.
>> Being from the United States I am of course ignorant of what system
>> anyone else uses. But I am enlightened enough to know that other people
>> have different ways of doing things.
>>
>> Just for the record, in case anyone is curious, in the USA we measure
>> fuel economy in Miles per Gallon, where a mile is about 1609 meters and
>> a gallon is about 3.78 liters.
>>
>> And I bet that in parts of the United Kingdom they also use Miles per
>> Gallon, but maybe those are Imperial Gallons(4.54 liters).
>>
>> For sure in true metric countries they must use metric units, but I have
>> heard it's reversed, and "Liters per 100 Kilometers" is a typical way of
>> specifying fuel economy. If this is so, is this the norm?
>>
>> So if you want to chime in with how you specify fuel economy and where
>> you live, it would be much appreciated (and the information will be used
>> in an upcoming open source PIC project).
>>
>> Thanks!
>>
>> Cheerful regards,
>> Bob
>>
>>
> Canadians typically express in litres/100km.
> South Africans typically express in litres/100km too, but also in
> km/litre sometimes (at least it was done 10 years or so ago).
>
> Just by the way, in most 'metric' places it is litre, not liter, and the
> SI unit is litre as well. You may want to get that right if you are
> planning to support international markets... ;-)
>
> Rolf
>
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[M. Adam Davis-2]

Thanks for asking this!  I had asked before but didn't get much
comment.  Now I nee to update my calculator:
http://driveslowly.org/13/mpg-and-savings-calculator

With options for
litres per 100km
litres per km
km per litre
miles per imperial gallon

Although, that nearly fills the problem space.  Need to keep it
simple, but I could make an advanced calculator with two options for
input, and three for output:
Volume units (Gallons, Imperial Gallons, Litres, Hogshead)
Distance units (Miles, KM, Furlongs)
Efficiency Measurement (Volume per distance, distance per volume)
Cost measurement (cost per volume, volume per cost, distance per cost,
cost per distance)

...should take care of the most common permutations, and allow for
simple expansion to add the odd measurements later...

-Adam


On Wed, Jul 9, 2008 at 5:58 PM, Bob Blick <bobblick@...> wrote:

> Apropos of the "best calculator" thread, I am curious about the
> different methods of measuring vehicle fuel economy across the globe.
> Being from the United States I am of course ignorant of what system
> anyone else uses. But I am enlightened enough to know that other people
> have different ways of doing things.
>
> Just for the record, in case anyone is curious, in the USA we measure
> fuel economy in Miles per Gallon, where a mile is about 1609 meters and
> a gallon is about 3.78 liters.
>
> And I bet that in parts of the United Kingdom they also use Miles per
> Gallon, but maybe those are Imperial Gallons(4.54 liters).
>
> For sure in true metric countries they must use metric units, but I have
> heard it's reversed, and "Liters per 100 Kilometers" is a typical way of
> specifying fuel economy. If this is so, is this the norm?
>
> So if you want to chime in with how you specify fuel economy and where
> you live, it would be much appreciated (and the information will be used
> in an upcoming open source PIC project).
>
> Thanks!
>
> Cheerful regards,
> Bob
>
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>
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> http://mailman.mit.edu/mailman/listinfo/piclist
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[M. Adam Davis-2]

On Wed, Jul 9, 2008 at 6:25 PM, Tomás Ó hÉilidhe <toe@...> wrote:
> For me, I make sure I get more fuel by stretching out the fuel tube so
> that I don't leave the petrol station with the tube still full of petrol.

Interesting!  In the US the valve is in the handle (at the end of the
tube) so the fuel stays in the tube once you shut it off (but you got
the fuel from the tube at the beginning, so even though it's measured
at the pump it all evens out)

-Adam

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[Bob Blick-4]

You can probably leave out Irish Miles (6721 feet) and Scottish Miles
(5951 feet) since they were officially put to rest in the year 1592 :)

Cheers,

Bob

P.S. what is a good abbreviation for "metres per 100km"?


On Wed, 9 Jul 2008 19:32:27 -0400, "M. Adam Davis" <stienman@...>
said:
> Thanks for asking this!  I had asked before but didn't get much
> comment.  Now I nee to update my calculator:
> http://driveslowly.org/13/mpg-and-savings-calculator
>
> With options for
> litres per 100km
> litres per km
> km per litre
> miles per imperial gallon

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[Bob Blick-4]

On Wed, 09 Jul 2008 16:50:07 -0700, "Bob Blick" <bobblick@...>
said:

> P.S. what is a good abbreviation for "metres per 100km"?


I guess the abbreviation for that would be 100000 or maybe 1E5 :)

But what I really wanted to write was "litres per 100km"

oops.

-Bob


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[Richard Prosser]

2008/7/10 Bob Blick <bobblick@...>:
> You can probably leave out Irish Miles (6721 feet) and Scottish Miles
> (5951 feet) since they were officially put to rest in the year 1592 :)
>
> Cheers,
>
> Bob
>
> P.S. what is a good abbreviation for "metres per 100km"?



10E-5 ??

RP
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[Rolf-4]

Tomás Ó hÉilidhe wrote:
> One thing about volume:  I know at least one person who tries to buy his
> petrol in the morning rather than later in the day because when it's
> cooler it's denser, so you get more mass for the same amount of money.
> As for how denser it is, I don't know.
>
> For me, I make sure I get more fuel by stretching out the fuel tube so
> that I don't leave the petrol station with the tube still full of petrol.
>  
Apparantly this one has some basis of fact, but more in fiction. Yes,
the colder fuel is more dense, and thus you get more enery density from
the pump, but, it ignores a 'fact' about the ground the petrol station's
tank is buried in (pretty much every fuel station has an underground
storage tank...), and that is that the temperature underground is pretty
constant (for example, in Canada (well, in southern ontario where i have
a little experience with this) we often have geo-thermal house furnaces
that use the ground at about 5feet deep as a heat exchange. The ground
temperature at 5feet deep is about 10 degrees summer or winter - from
+30 in the summer to -30 in the winter). As a result, the fuel you get
in your car is going to be the same temperature regardless of when you
fill up.

The best you can hope for is that (in the summer) the fuel has been in
the tank for a while and cooled down from the deliver truck, and in
winter, it is fresh in the tank from the delivery truck.

More on that here:

http://www.snopes.com/inboxer/household/gastips.asp

and on geothermal heat pumps:

http://en.wikipedia.org/wiki/Geothermal_heat_pump

Rolf
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[Rolf-4]

Richard Prosser wrote:

> 2008/7/10 Bob Blick <bobblick@...>:
>  
>> You can probably leave out Irish Miles (6721 feet) and Scottish Miles
>> (5951 feet) since they were officially put to rest in the year 1592 :)
>>
>> Cheers,
>>
>> Bob
>>
>> P.S. what is a good abbreviation for "metres per 100km"?
>>    
>
>
>
> 10E-5 ??
>
> RP
>  

Uhm... wouldn;t that be 10e5 not 10e-5?

Rolf
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[Olin Lathrop]

Rolf wrote:
>>> P.S. what is a good abbreviation for "metres per 100km"?
>
> Uhm... wouldn;t that be 10e5 not 10e-5?

Neither.  Try 1e5.

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[Tomás Ó hÉilidhe-2]

Rolf wrote:
>>> P.S. what is a good abbreviation for "metres per 100km"?
>>>    
>>>      
>>
>> 10E-5 ??
>>  
>>    
> Uhm... wouldn;t that be 10e5 not 10e-5?
>  


One metre is:    10 to the power of 0

100 km is:    (10 to the power of 2) multiplied by (10 to the power of
3), which gives a total of 10 to the power of 5

Because it's "per", you divide, so you've got:

    10e0    divided by    10e5

As you know with indices, you add for multiplication, and subtract for
division, so you're left with:

    10e(0-5)

which is:

    10e-5

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[Jinx-4]

> For me, I make sure I get more fuel by stretching out the fuel tube
> so that I don't leave the petrol station with the tube still full of
petrol

I've heard that described as 'moral theft', because you're stealing off
the next customer

> Yes, the colder fuel is more dense, and thus you get more energy
> density from the pump

ISTR McLaren were investigated in a recent F1 race for having their
fuel bowser at less than regulation temperature

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[Tomás Ó hÉilidhe-2]

Tomás Ó hÉilidhe wrote:
> Because it's "per", you divide, so you've got:
>
>    10e0    divided by    10e5


Crap that should have been:

    1e0    divided by     1e5

or:

   10^0    divided by    10^5

I hate when I make that mistake!


> As you know with indices, you add for multiplication, and subtract for
> division, so you're left with:
>
>    10e(0-5)


Again, should  be:

   1e(0-5)


> which is:
>
>    10e-5


So my final answer is:  1e-5   or   10 ^ -5



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[Tomás Ó hÉilidhe-2]

Tomás Ó hÉilidhe wrote:
> Because it's "per", you divide, so you've got:
>
>    10e0    divided by    10e5



Oh God I'm wrong again.


1 metre is 10^1, not 10^0.


So if you've got metres per 100 km, then that's  m^1    /   m^5


Then that gives you:   m ^ -4


Hopefully this is the last time I correct myself on this!


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