MPG or L/KM?

SpannerMonkey · 02-06-2013 06:16PM

mpg for me and im only 29 , cant figure out l/100km , but prefer the metric system for everything else

djimi · 02-06-2013 06:43PM

CiniO wrote: »

Obviously both can be used to calculate the same thing.

But hence that l/100km shows how much fuel you'll need to travel certain distance.
km/l shows how much distance you can travel on certain amount of fuel.

People in vast majority of cases need to know the first thing (how much fuel you'll need to travel certain distance).

It's just easier for calculations then.
You take your consumption f.e. 7.4 l/100km and multiply it by amount of 100s of kilometres you want to travel. So f.e. you want to travel 250km, then it's 7.4*2.5 = 18.5 litres. That's calculation I was able to do in my head within few seconds, even though both factors contains fractions.

7.4 l/100km is 13.5 km/l. If you want to travel 250km, you need division. 250 / 13.5 = ???? We already know it's 18.5 litres, but that's not the calculation I car do easily in my head.

Your example made it equally easy as you just choose adequate amounts. I chose random amounts, and you can see it makes a difference.
Multiplying in your head is way easier than dividing.

Besides - if Irish people are to convert from imperial units to metric units, why do it the wrong way? I mean why create an unit like km/l which probably isn't used anywhere in the world while you can just use l/100km which is used nearly everywhere. Doesn't make sense.

Its exactly the same. 3l/100Km tells me that for 100km I need 3 litres of fuel. 20km/l tells me that for 100km I need 5 litres of fuel. There is absolutely no difference whatsoever. Both tell you how much fuel per km; one is just written the other way around!

Does it really matter whether or not you can work it out in your head? Even the most basic phone nowadays has a calculator; it should take no more than 30 seconds either way to calculate.

dr.fuzzenstein · 02-06-2013 07:28PM

djimi wrote: »

Its exactly the same. 3l/100Km tells me that for 100km I need 3 litres of fuel. 20km/l tells me that for 100km I need 5 litres of fuel. There is absolutely no difference whatsoever. Both tell you how much fuel per km; one is just written the other way around!

Does it really matter whether or not you can work it out in your head? Even the most basic phone nowadays has a calculator; it should take no more than 30 seconds either way to calculate.

3l/100 km? What car you drive?;)

CiniO · 02-06-2013 08:50PM

djimi wrote: »

Its exactly the same. 3l/100Km tells me that for 100km I need 3 litres of fuel.

It tell you this directly.

20km/l tells me that for 100km I need 5 litres of fuel.

It tells you this indirectly - you need to do calculation.
And while in your example they are very easy, but in many cases they might not be easy.

There is absolutely no difference whatsoever. Both tell you how much fuel per km; one is just written the other way around!

One is just written the other way around, so you can turn it over yourself to know... What's the point of this hassle.

Does it really matter whether or not you can work it out in your head? Even the most basic phone nowadays has a calculator; it should take no more than 30 seconds either way to calculate.

Yes, but why should I take calculator out and use 30 seconds to calculate while when using l/100km I can do it in my head in 5 seconds.

km/l is just not natural considering more people want to know how much fuel they need to drive certain distance, then how much distance can they drive having certain amount of fuel.
Imagine going to the shop. You have prices like 1.50 euro per can of beer, 25 euro per kg of beef, or 4 euro per box of chocolate.
In your way of thinking, price labels should read something like:
- 6.66 cans of beer for 10 euros
- 0.4 kg of beef for 10 euros.
- 2.5 box of chocolatef for 10 euros.

Does it look normal - no?
Could it work like that - sure. People would know who much they are going to pay as everyone has calculator in their mobile those days.
But what's the point if everyone is using it opposite way?

The same with fuel consumption - what's the point to introduce km/l system which is less convienant and everyone is using the other way - l/100km.

02-06-2013 10:31PM

CiniO wrote: »

It tell you this directly.

It tells you this indirectly - you need to do calculation.
And while in your example they are very easy, but in many cases they might not be easy.

One is just written the other way around, so you can turn it over yourself to know... What's the point of this hassle.

Yes, but why should I take calculator out and use 30 seconds to calculate while when using l/100km I can do it in my head in 5 seconds.

km/l is just not natural considering more people want to know how much fuel they need to drive certain distance, then how much distance can they drive having certain amount of fuel.
Imagine going to the shop. You have prices like 1.50 euro per can of beer, 25 euro per kg of beef, or 4 euro per box of chocolate.
In your way of thinking, price labels should read something like:
- 6.66 cans of beer for 10 euros
- 0.4 kg of beef for 10 euros.
- 2.5 box of chocolatef for 10 euros.

Does it look normal - no?
Could it work like that - sure. People would know who much they are going to pay as everyone has calculator in their mobile those days.
But what's the point if everyone is using it opposite way?

The same with fuel consumption - what's the point to introduce km/l system which is less convienant and everyone is using the other way - l/100km.

Looks normal to me, I always convert to how many cans or bottles of beer I'm getting for x amount of money or how may steaks I'm getting for for x etc!

Mr.David · 02-06-2013 11:24PM

Have a look at the attached spreadsheet, for calculating the cost of driving 100miles at various mpg values. you can see that if you have a car that does 10mpg it will cost 68euro. to halve this cost you need to move to 20mpg i.e. 34 euro. to halve this again you need to move to 40mpg etc etc.....diminishing savings as you increase in mpg.

at 55mpg it costs 13.62, and at 60mpg you only save an additional euro.

you can see that the l/100m is linear by comparison.

apologies for the poor explanation, im really hungover and struggling to think clearly and form proper sentences here!

johndaman66 · 03-06-2013 12:05AM

I'm Irish, not European, hence I tend to stick with the trusted MPG. 5.7 litres per 100km means very little to me. If you do work in litres per 100 km thats just fine though but don't expect me to do the same....

Yakuza · 03-06-2013 12:32AM

I'm Irish (and European!) and I've fully embraced l/100 KM (moreso since 2010 when I bought my first car that had KM only in the speedo). Given that most dashes and all road signs here are in KM, and we purchase fuel in litres, it makes working out your car's consumption trivial.

I can also convert into MPG if needs be - a very good rough estimate is to divide whatever figure you have into 280 and that will give the other figure (7l/100km = 280/7 ~ 40MPG, 10l/100km ~ 28 MPG, 50MPG ~ 5.6 l/100km).

Just as I stopped thinking in pounds when my payslips started appearing in euro, I stopped thinking in miles and when my car became denominated in km (but I can still convert back if ever needed).

Matt Simis · 03-06-2013 12:47AM

johndaman66 wrote: »

I'm Irish, not European, hence I tend to stick with the trusted MPG. 5.7 litres per 100km means very little to me. If you do work in litres per 100 km thats just fine though but don't expect me to do the same....

You are European, you are in an EU country and the EU as a region uses L/100km and all the talking about good old says and little stretches of sea between our Islands and the rest of our Union doesnt in any way change the reality of being "in Europe".

As an aside, L/100km is used in loads of places well outside "Europe":

Units of fuel per fixed distance
Generally expressed as liters per 100 kilometers (L/100 km), used in Europe, China, South Africa, Australia and New Zealand and Canada

Its used in places that you know.. arent backward.
Funny people on the otherside of the planet using it yet people in Ireland, in Europe, expressing such furrowed brows at the concept.

dr.fuzzenstein · 03-06-2013 01:03AM

johndaman66 wrote: »

I'm Irish, not European, hence I tend to stick with the trusted MPG. 5.7 litres per 100km means very little to me. If you do work in litres per 100 km thats just fine though but don't expect me to do the same....

Even Ireland is using the metric system nowadays. As everything else, it happened decades later, but it happened.
And you are European. Geographically and politically.

Marcin_diy · 03-06-2013 02:45AM

Mandzhalas wrote: »

road signs shows distance in kilometers
petrol stations pumps shows amount in litres
car speedos displays in km/h (from 2004)
why on earth use mpg???

Did Ireland not fully introduced metric system in 2005 and car speedos in 2006?

To stop some crazy discussions above i suggest to fill fuel tank to the top and just drive :-)

We are on motors forum and we drive the best machines we can afford so who cares about fuel. When I buy a car, I buy it because I like it, interior is nice, exterior is fine and it is quick. I wouldn't buy a car I don't like visually only cos it has 1 or 2 l /100km better fuel consumption. It makes no sense for me. I wouldn't change my 2L petrol vtec for a 1L yaris to get a twice better fuel economy . The only factor I consider related to fuel is fuel price and I avoid places where I overpay compared to other places around.

I hope I'm not the only one here with this point of view.

dr.fuzzenstein · 03-06-2013 12:04PM

Marcin_diy wrote: »

Did Ireland not fully introduced metric system in 2005 and car speedos in 2006?

To stop some crazy discussions above i suggest to fill fuel tank to the top and just drive :-)

We are on motors forum and we drive the best machines we can afford so who cares about fuel. When I buy a car, I buy it because I like it, interior is nice, exterior is fine and it is quick. I wouldn't buy a car I don't like visually only cos it has 1 or 2 l /100km better fuel consumption. It makes no sense for me. I wouldn't change my 2L petrol vtec for a 1L yaris to get a twice better fuel economy . The only factor I consider related to fuel is fuel price and I avoid places where I overpay compared to other places around.

I hope I'm not the only one here with this point of view.

Well, the first point, I drive the nicest thing I can afford, but because I have to commute over 60 km a day and my income has to run the entire household, I care a great deal about fuel. Because I spend nearly 2 hours a day in my car and the commute, it had to be roomy, comfy and good on the juice.
Therefore CMax, it does 50 mpg (why do I use MPG? See below) and the 1.8 daysul has nice torque and won't ruin me (unless the clutch goes again;))
As for your second point, if half your salary went on the mortgage and the other half will have to cover everything else (and you're actually running out of money two weeks before payday, no matter how stingy you are), you'd be in a Yaris faster than your 2 litre VTEC will go from 0 to 100 (km/h of course).
We appreciate good motors here, aside from the odd troll who only frequents the motoring forum because they despise cars and want us all to drive at 30 km/h, or better still, cycle, but sometimes (or sadly most times) you have to make a compromise.
I'd love to drive a 1977 Mercedes 450SEL 6.9, but there's no chance of that right now.
I was actually very concerned when my average MPG dropped from around the 50 mark to the 47 mark, but new clutch and DMF fixed that.

Funniest thing: My car is actually set to MPG instead of l/100 km.
Why? Because Ford thought it would be funny to stick mpg into the metric setting and l/100 km in the medieval settings list.
And I have to say that MPG annoys me less than seeing the temperature in Fahrenheit, another arbitrary, illogical measurement, where somebody said "screw all that water boiling nonsense, I say zero goes thereabouts and let's just throw a dart at it to see where 100 goes"
What can I say, it's BH Monday and I felt like a little write up.

Stinicker · 05-06-2013 10:59PM

Having thought about this a little more, I have found this link and we can all agree to disagree and this can help us work out out MPG's from L/Kms!

http://www.markporthouse.net/rangie/fuelconsumptionconversion.htm#

joujoujou · 06-06-2013 02:31PM

Even google can calculate mpg to l/100km or km/l or back again if asked properly.

Example.

Also found quite nice page which allows to calculate mpg or l/100km or km/l stuff based upon one's refueling and distance done.

http://www.guycroft.clara.net/utils/mpg.html

Dr. Kenneth Noisewater · 06-06-2013 04:58PM

I was raised on MPG. Its too late to change, the same way that 77 degrees fahrenheit or 89 kg mean nothing to me. Its 25 degrees and im 14 stone!

dr.fuzzenstein · 06-06-2013 09:20PM

deccurley wrote: »

I was raised on MPG. Its too late to change, the same way that 77 degrees fahrenheit or 89 kg mean nothing to me. Its 25 degrees and im 14 stone!

Celcius being the odd one out in that list!:pac:

Merch · 07-06-2013 12:00AM

I keep meaning to get used to L/100km, but it just doesnt seem natural, ok so plenty of other countries use it, its the standard.

That its been described as a matter of efficiency and consumption seems a bit odd.

Dont get me wrong, Im all for metric units in use, but L/100 km doesnt seem as useful for short journeys, just as there isnt a useful comparable unit to the foot, metric isnt the be all and end all.
Im not really going to go to the trouble of calculating how much fuel I need for a short journey, but I am interested to know what the average efficiency of what Im driving is.

Units geared to Consumption then is useful for determining how much I need for a long journey, more so.
but Im still interested in the efficiency of my vehicle.

Im not convinced comparing why some product is priced per kg
and another is measured in l/km is a useful comparison. An analogous unit to mpg which people could use to convert themselves from imperial to metric must be km/l, if they want to compare like for like.

I can just as easily say 5l/100km is the same as 20km/l, if I have a 10, 100 or 300 km journey I can quickly work out just how much fuel I need and see what my efficiency is at the same time,m no?

I guess I will just have to get used to l/100km, but I can still use l/km in my own head.

rocky · 07-06-2013 02:58PM

I'm using l/100km , but can convert to MPG by dividing 280 to l/100km and viceversa. And I know 15.5l/100km is 18 mpg

MPG or L/KM?

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