MPG or L/KM?

Mint Sauce

Title says it all really.

Dispite the fuel pumps reading in litres, and my odometer reading km's, still somehow better understand MPG my self. Not sure if its the MPG we were all used to hearing, and having miles on our cars on road signs for so long. Even switch my fuel diary back to miles and gallons, after entering the consumption and refill in km's and litres.

Supergurrier

I think in mpg anyway.

For metric system I need a calculator

SCOOP 64

Same here only think in mpg, only relised the other day i can set my trip computer in the zafira to mpg instead of klm and i have it for 3years!.

650Ginge

If you stick with one it is ok you will understand it. Bit we get so much car review and info from uk sites where they only do mpg that it all gets confusing.

I stick with Uk mpg on fuelly, but kinda have my head around l/100kms. But u just find it is not acturate enough. I mean 4.5 and 4.6 is a difference of 0.1, but in miles it a difference of nearly 2 miles to gallon difference.

I might give k/l a try, thinking about it it makes the most sense. You can quickly see the price of a litre and how far you get for it.

Sam Russell

28.25 miles per gallon equates to 10 l per 100 km.
5 l/100km equates to 56.5 mpg.

But I still think in mpg.

CiniO

Litres per 100km for me.

MPG is ridiculous - mostly due to confusion that gallon is different in UK and America.
So in addition to specifying fuel economy in MPG you have to tell if you mean imperial mpg or us mpg.

SI system is the best system of units invented so far. It's used all over the world for science.

And as OP said - as we measure distances in km in Ireland and fill up cars in litres, using MPG to show fuel consumption just makes life much harder.

km/l is just a way people used to mpg see how to switch to metric system.
No one from countries using metric system for longer time use this.

Sobanek

I always calculate in l/100km.

Leonard Hofstadter

MPG for me. First thing I do in a car with the clocks in kms is to see can I switch the trip computer to display mpg. Especially as I'm now living in the UK, it is far easier to do mpg anyway. I have no problems using kms for distance or thinking of speeds in kph, but the conversion from mpg to l/100 km is too complicated. I don't know why we can't just use km/l for metric fuel consumption anyway - it makes far more sense than l/100 km.

CiniO

captainspeed wrote: »

I don't know why we can't just use km/l for metric fuel consumption anyway - it makes far more sense than l/100 km.

Why does it make more sense?

Stinicker

MPG all the way, L/100km is complete utter stupidity; if it was Kilometers per Litre then at least you'd have an accurate idea of your consumption but L/100km must have been deliberately invented to confuse people and trick them into buying cars which are actually worse than they are marketed.

ibebanging

Stinicker wrote: »

MPG all the way, L/100km is complete utter stupidity; if it was Kilometers per Litre then at least you'd have an accurate idea of your consumption but L/100km must have been deliberately invented to confuse people and trick them into buying cars which are actually worse than they are marketed.

Miles and gallons ? Move on ! We now pay for litres in €'s to......

Cee-Jay-Cee

I bought my first Japan import car in 1997 and every car since has been in knob and so I measure distance and speed in Kms but still work out fuel economy in mpg, my fuel computer is in l/100km but I have it worked out so that I know what the equivalent mpg figure is.

CiniO

Stinicker wrote: »

MPG all the way, L/100km is complete utter stupidity; if it was Kilometers per Litre then at least you'd have an accurate idea of your consumption but L/100km must have been deliberately invented to confuse people and trick them into buying cars which are actually worse than they are marketed.

Why would you have an idea with kilometres per litre, while you dont with l/100km ?

l/100km is really clear.

Say you car uses 5 l/100km.

You have 200km journey - so you know you will need 10 litres.

Can't really think of easier system.

Stinicker

ibebanging wrote: »

Miles and gallons ? Move on ! We now pay for litres in €'s to......

I visualize distances in miles and can think in miles, I measure in Metric etc. but for me Miles are king. I don't have a problem with Kilometres but L/100kms is utter crazy, I want to know how many units of measurement I can travel for another unit of measurement thus it should be kms per litre a simple and easy to understand formula where you don't need a calculator to work it out.

I was against the Metricification of speed limits simply because we share a border with the North and also Ireland is not a part of Europe nor will we ever be. Ireland and the UK are two islands off the coast of Europe similar to the Falkland islands off South America we live near them but we are nothing like them or have anything in common. The UK will leave the European Union shortly and Ireland by default will also have to leave unless the Government is willing to seal the border to the North and that won't happen.

Metric=Europe=Not Ireland

Jesus.

MPG all the way. Also MPH for speed and miles for distance. Any time I see a speed sign or look at my speedometer I immediately convert it into miles.

Whatever you were brought up with you're going to continue using. Well, a lot of people will anyway.

CiniO

Stinicker wrote: »

I visualize distances in miles and can think in miles, I measure in Metric etc. but for me Miles are king. I don't have a problem with Kilometres but L/100kms is utter crazy, I want to know how many units of measurement I can travel for another unit of measurement thus it should be kms per litre a simple and easy to understand formula where you don't need a calculator to work it out.

What do you need calculator for with l/100km?
Look at my example above - no calculator needed.

With MPG - you definitely do need calculator.

F.e. you need to travel 500km. How many litres of fuel will you need to put in the tank to do it, knowing your car does 40MPG.
Do it without a calculator and unit conversion values.

I was against the Metricification of speed limits simply because we share a border with the North and also Ireland is not a part of Europe nor will we ever be.

This is quite ridiculous statement.

Ireland and the UK are two islands off the coast of Europe similar to the Falkland islands off South America we live near them but we are nothing like them or have anything in common.
The UK will leave the European Union shortly and Ireland by default will also have to leave unless the Government is willing to seal the border to the North and that won't happen.

Metric=Europe=Not Ireland

Even if UK leaves EU what kind of boarder sealing you mean?
Ireland an UK are anyway not part of Schengen zone, so there are border checkes between them and Continent.

Leonard Hofstadter

CiniO wrote: »

Why would you have an idea with kilometres per litre, while you dont with l/100km ?

l/100km is really clear.

Say you car uses 5 l/100km.

You have 200km journey - so you know you will need 10 litres.

Can't really think of easier system.

If you have 10 litres in the tank, and car does 8.9 l/100 km then it's not possible to work out how far you can go before you need to refill without a calculator. If you know it's doing say 8 km per litre then you instantly know there's 80 km (50 miles) left before you're out of fuel.

If you're brought up with mpg, then km per litre makes sense in a way that l/100 km does not. From a maths point of view it's clearly much easier to go from mpg to km per litre, 10 km per litre is approximately 28 mpg so if one is given a km/l figure a very rough conversion is to multiply by 3 to get the mpg figure instead. Low l/100 km is good, low mpg is bad. With km/l more is better the same way more mpg is better.

We don't measure speeds in hours per 100 km and for good reason too. Using l per 100 km for fuel makes as much sense as hours per 100 km does for speed.

I happen to think that Ireland should never have changed from miles to km until such time as the UK did, not least because Ireland shares a land border with a country that's still using miles. We've succeeded in confusing things where there was no need to. From a cars point of view, it makes UK imports less attractive on the second hand market, since they obviously are still using miles and so any car imported from there will have mph clocks. On the other hand, using kms is clearly to our benefit every time we go anywhere in the world except the UK and US, so we probably were right to make the switch. Ireland also should not merely copy everything Britain does and not change something because they won't.

Matt Simis

Stinicker wrote: »

I was against the Metricification of speed limits simply because we share a border with the North and also Ireland is not a part of Europe nor will we ever be. Ireland and the UK are two islands off the coast of Europe similar to the Falkland islands off South America we live near them but we are nothing like them or have anything in common. The UK will leave the European Union shortly and Ireland by default will also have to leave unless the Government is willing to seal the border to the North and that won't happen.
Metric=Europe=Not Ireland

Jesus christ,... are you out of the time capsule long?


Ignoring the geo-politicical insanity above, to the op, try this:

Dont try to mentally convert L/100km to MPG. Just like when you got paid in Euros at first you mentally converted it to punt, but it only "makes sense" when stopped converting it and use it as is. For Stinicker, visualise moving from shillings to decimal currency.


The reason L/100 isnt "making sense" is L/100km is a measure of consumption. MPG is a measure of efficiency. L/100km is not a "metrification" of MPG, expecting it to be is a source of confusion. The metric version of MPG is KM/L, which no one uses. The US want to move their even more antiquated version of "MPG" to a consumption system too, over to Gallons per MIle.

So when you are driving and you look at the computer readout, dont think "how efficient is my driving", think "how much fuel which I bought in litres am I consuming over my trip"*. You actually pay for consuming fuel, not for how efficient you drive (which is merely a multiplier on consumption/reserve remaining over time).

Once you move to/accept that simple logic, L/100 is a fantastic system.


* Obviously this is consumption over a 100km trip, which is a large enough distance to present impactful "understanding" of consumption.

T-Maxx

Another vote for km/l

Leonard Hofstadter

Matt Simis wrote: »

The metric version of MPG is KM/L, which no one uses. The US want to move their even more antiquated version of "MPG" to a consumption system too, over to Gallons per Mile.

On the contrary the US are very much NOT changing to a gallons per mile system, they just brought out a 'miles per gallon equivalent' to measure the efficiency of electric cars. One of the reasons they did this was because focus groups showed that kWh per 100 miles was both confusing and unpopular with American consumers. Thus all the Federal tests for the efficiency of Electric cars will now show consumption in mpge.

Matt Simis

captainspeed wrote: »

On the contrary the US are very much NOT changing to a gallons per mile system, they just brought out a 'miles per gallon equivalent' to measure the efficiency of electric cars. One of the reasons they did this was because focus groups showed that kWh per 100 miles was both confusing and unpopular with American consumers. Thus all the Federal tests for the efficiency of Electric cars will now show consumption in mpge.

On the contrary yourself.
Im referring to the lobby group(s), social commentators, educated minority in the US that are pushing for a consumption system as its more relevant, you buy fuel, you consume it. You buy food, you consume it. You dont measure bread in bites per swallow.

The fact a US focus group found kWh per 100miles "confusing" is not a revelation, apart from the fact they dont use a consumption system at the moment, kWh is a metric energy consumption rating and 100miles is an arbitary SI unit... FFS you couldnt present a more stupid system to a focus group and couldnt find a more insular (to be polite) society to do it in.



All this arguing and justifications aside, what this comes down to is people able to understand a new system and those who cannot/will not adapt. We live in a metric world (thankfully), fight it all you want, but its pissing in the wind.

CiniO

captainspeed wrote: »

If you have 10 litres in the tank, and car does 8.9 l/100 km then it's not possible to work out how far you can go before you need to refill without a calculator.

Without a calculator and having though about it for less than 5 seconds, I can tell you that I can go slightly over 100km (possibly about 110 - 115).
If you want exact figure - yes - I need a piece of paper for calculations or calculator.

If you know it's doing say 8 km per litre then you instantly know there's 80 km (50 miles) left before you're out of fuel.

But if you need to travel 300km, and know that your car is doing 8km per litre, how much time do you need to calculate how much fuel you need without calculator?

Leonard Hofstadter

CiniO wrote: »

But if you need to travel 300km, and know that your car is doing 8km per litre, how much time do you need to calculate how much fuel you need without calculator?

8 km per litre X 40 litres = 320 km, that was easy. So fill with 40 litres and you've more than enough (it's a bad idea to let the tank run dry anyway). Knowledge of the multiplication tables makes it easy to work out situations like the above. It's exactly 37.5 litres for what it's worth, 2.5 X 8 = 20, and 320-20=300. Unless one is totally numerically illiterate, none of the above requires a calculator. Again the maths of this is a lot more straightforward than using l/100 km to work out fuel consumption - working out exactly how many km you can travel when you have 10 litres but the car is doing 8.9 l/100 km requires long division at least and really it needs a calculator to get an exact answer.

Bohrio

captainspeed wrote: »

8 km per litre X 40 litres = 320 km, that was easy. So fill with 40 litres and you've more than enough (it's a bad idea to let the tank run dry anyway). Knowledge of the multiplication tables makes it easy to work out situations like the above. It's exactly 37.5 litres for what it's worth, 2.5 X 8 = 20, and 320-20=300. Unless one is totally numerically illiterate, none of the above requires a calculator. Again the maths of this is a lot more straightforward than using l/100 km to work out fuel consumption - working out exactly how many km you can travel when you have 10 litres but the car is doing 8.9 l/100 km requires long division at least and really it needs a calculator to get an exact answer.

so hold on, you dont need a calculator to do the above but you need one to calculate how many km will your car run for if you have 10 liters left and your car consumption is 8.9 l every 100 km?

I mean, even without thinking I can tell you it will be a little bit over 110 km

L every 100 km is a very practical way of measuring fuel consumption, I mean, we use km to measure distances, litres when we pump fuel at a petrol station.

Imagine (lets pretend) how this will work for someone who just arrived to Dublin from another country, he rents a car and goes to the petrol station to put fuel in, he going to Galway, looks at the map and sees galway is approximately 200 km away (lets just say it is), checks the car manual and read that his car does 30 mpg...

And that part where you said Ireland isnt in Europe I am not quite sure about that one either...

CiniO

captainspeed wrote: »

8 km per litre X 40 litres = 320 km, that was easy. So fill with 40 litres and you've more than enough (it's a bad idea to let the tank run dry anyway). Knowledge of the multiplication tables makes it easy to work out situations like the above. It's exactly 37.5 litres for what it's worth, 2.5 X 8 = 20, and 320-20=300. Unless one is totally numerically illiterate, none of the above requires a calculator. Again the maths of this is a lot more straightforward than using l/100 km to work out fuel consumption - working out exactly how many km you can travel when you have 10 litres but the car is doing 8.9 l/100 km requires long division at least and really it needs a calculator to get an exact answer.

To travel 300km with 8.9 l/100km consumption it's 8.9x3 = 26.7 litres. No need for calculator again.

On 10 litres you can travel over 100km, but the same as you said - it's a bad idea to let the tank dry - so assume you have more than enough to travel 100km.

As you can see both are pretty simple...
And depending on situation requires more or less calculations, but absolutely doesn't make one or the other more difficult to calculate....

MPG is different story as you need to convert litres to gallons and miles to km so it's awkward calculations.

But km/l or litres/100km are equally easy.

And if so, what's the point in using km/l while most of the world uses l/100km.

ION08

L/100km make so much more sense than the backwards MPG system.

Its so much more logical as its based on consumption as opposed to efficiency

If your car uses on average 6l/100km, you know that (depending on prices) youll get get roughly 100km (or 60miles if your cars clocks are in mph) for a 10ers worth of fuel.

When youre finished pumping fuel, simply look at the amount of litres you put in and facto your cars average consumption into.

As a quick example: i put €30 into my car, it says on the pump readout that i got 21 Litres. I know my car averages around 7L / 100 km - so im Instantly able to determine that i will be able to drive 300km for the amount ive put in.

Similarly I can easily judge that if i need to travel a distance of say 100km somewhere itll cost me approx a 10er worth of fuel (as my car averages 7/100km, and 7 litres is what i get for a tenner at the pump)

So if i need to go 50km i know ill need roughly a 5er or petrol etc.

It couldnt be anymore logical! .. Especially considering tgat we buy LITRES of fuel and we travel distances in Kilometers!

Ps. Apologies for the terribly written post, typed it quickly from my phone :P

spank_inferno

KM / Litre ftw.

I cannot get my head around L / 100 KM.

dgt

Mpg. I know what my car does, I know how far I'll go with what I have in my tank.

Why change something that works for me?

YouTookMyName

Kilometres per gallon

Miles per litre

FTW.

Max Power1

YouTookMyName wrote: »

Kilometres per gallon

Miles per litre

FTW.

I prefer miles per liter tbh

HandsomeDan

Stinicker wrote: »

MPG all the way, L/100km is complete utter stupidity; if it was Kilometers per Litre then at least you'd have an accurate idea of your consumption but L/100km must have been deliberately invented to confuse people and trick them into buying cars which are actually worse than they are marketed.

Daft thing to say. One is just the reciprocal of the other. A child could get its head around that (or even a Daily Mail loser)?

The choice of one over the other is completely arbitrary - just a question of what you're used to.

joujoujou

I wish we all have had only such big problems really. :P

I don't care what is best for him, for her, whatever.

I'm using litres per 100 kilometres myself, because I got used to.

If anyone else find other way is better for him/her - it's not my problem.

gizabeer

MPG all the way

YouTookMyName

Max Power1 wrote: »

I prefer miles per liter tbh

Sobanek

To the person that gave 8.9l/100km example.

What if my car does 37.3 mpg and I have 7.3 gallons in my fuel tank? Huh?

dgt

Sobanek wrote: »

To the person that gave 8.9l/100km example.

What if my car does 37.3 mpg and I have 7.3 gallons in my fuel tank? Huh?

Are you drunk again..... :pac:

Seriously, it was a silly statement to make, who knows whats in the tank till its drained and measured

CiniO

dgt wrote: »

Are you drunk again..... :pac:

Seriously, it was a silly statement to make, who knows whats in the tank till its drained and measured

Person who initially asked about 8.9 l/100km asked how much can you drive on 10 litres.
Who did he know there was 10 litres in the tank?

dgt

My point exactly, how would one know whats in the tank, pump and lines?

Sobanek

Some old cars like the BMW E32 actually tell you how much fuel you have:



dgt, that's the point I was making... How would I know how much fuel I have left, and how would he know he has 10 litres in his tank.

joujoujou

Sobanek wrote: »

Some old cars like the BMW E32 actually tell you how much fuel you have:

[...]

Some new ones actually can tell you how many kilometres/miles you can make on fuel you have in tank.

Anyway, it's an estimate only, as well as howmuchfuelyouhave thing.

Sobanek

joujoujou wrote: »

Some new ones actually can tell you how many kilometres/miles you can make on fuel you have in tank.

Anyway, it's an estimate only, as well as howmuchfuelyouhave thing.

Even the car above has "Range" in its computer

CiniO

dgt wrote: »

My point exactly, how would one know whats in the tank, pump and lines?

So in general, you mean there's more often a need to know how much fuel you need to travel certain distance, than knowing how much distance you can travel on certain amount of fuel. At least that what I undestand concludes what you meant.

And if so, l/100km is way better measurement for calculating amount of fuel needed for certain distance than mpg or km/l.

It really makes sense.
How many people wake up in the morning, and think to themselves - I've got 4 gallons of fuel in my tank. My car does 40MPG. So I can travel 160miles. Therefore I can go to Cork and back today, as it's only 78 miles to get there.
I'd say not many.

Most people wake up in the morning, and think to themselves - I need to get to Dublin and back today. It's 300km each way, so I need to travel 600km.
My car does 6 l/100km, so I'll need 6*6 = 36 litres of fuel. Then you go to petrol station, fill'er up by 36 litres and off you go to Dublin.
This makes perfect sense.

HandsomeDan

CiniO wrote: »

Most people wake up in the morning, and think to themselves - I need to get to Dublin and back today. It's 300km each way, so I need to travel 600km.

That's unbelievable! That's exactly what I thought this morning. And I wasn't even going to Cork today?

dgt

Zut alors! My tiny brain is fried here.....

I fill up with what I estimate I'll need for the next week. Good planning and all that. I rarely get caught out too

I work with mpgs as its what works for me, what I'm used to. I know what I have, estimate my range and work with a small margin of error. Why should I change what works for me?

To confuse things further I work with time and not distances. I look at a sign with 20kms distance left and est my time of arrival at about 15 mins at 80 kmh constant, realistically 20 accounting for numpties, braking and other external forces.

Don't try change me, I'm stuck in my ways. What most people do I'll usually rebel against it anyway

HurtLocker

I'm thrown between the two. I use L/100km the dash for current consumption but when I use the Road Trip app I leave it on MPG. I don't know why it makes sense to me. Although I keep an idea in my head of €/km so I've an idea of how much fuel I've used and how much it'll cost me to refill. Nice easy to remember €0.10 per km at the moment.

Mandzhalas

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???

Jesus.

joujoujou wrote: »

Some new ones actually can tell you how many kilometres/miles you can make on fuel you have in tank.

Funny you should mention that, joujoujou, I've got one of those settings on my new (10 yr old!) Motor. I've only had the car two weeks so I only had the petrol down low once. That setting showed about 70 miles left in the tank before I ran out but when the "fuel up" light came on, that setting disappeared.

Why wouldn't it continue giving me estimates just cos the fuel light came on?

TheChizler

Poster up above hit it on the head, when starting a journey the distance you need to go is fixed, you want to know if you have enough fuel to cover that fixed amount. You don't pick your destination based on how much fuel you have. Volume of fuel per distance makes sense in this context.

Even if you have the wrong one a quick estimate in your head is good enough, the efficiency/consumption is going to be changing constantly anyway so even if you use a calculator it's going to be nowhere near accurate.

_Kaiser_

This may be useful for some.. MPG to l/100 km converter

evolutionqy7

L/100 km

Kind awkward to work out liters into gallons and then kilometers into miles.

Metric is more straight forward for me anyway

BMJD

I don't give a hooting hoot how far my upcoming journey is! If it's nearly empty, I fill 'er up, end of.