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metres per cubic metre (m/m³) Kilometres per litre (km/L) miles per gallon (U.K) (mi/gal) miles per gallon (U.S) (mi/gal) Litres per 100km (L/100km)

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to metres per cubic metre (m/m³) Kilometres per litre (km/L) miles per gallon (U.K) (mi/gal) miles per gallon (U.S) (mi/gal) Litres per 100km (L/100km)

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Fuel consumption is generally expressed as MPG (Miles Per Gallon) but nowadays the expression litres per 100km (L/100km) is also becoming popular.
The information in the table below provides a method of converting from MPG to the listed expression.

Scheme	Convert to	Multiply MPG by
U.S. gallon	Metres per Cubic meter (m/m³)	425 143.7
U.S. gallon	Kilometre per litre (km/L)	0.425 143 7
U.K. & Canada gallon	Metres per Cubic meter (m/m³)	354 006.2
U.K. & Canada gallon	Kilometre per litre (km/L)	0.354 006 2

To calculate Litres per one hundred kilometres (L/100km) first calculate the Kilometres per Litre (km/L) using the above table then divide 100 by this km/litre value.

For example you have a truck that returns 25mpg (based on U.S. gallons) and you wish to compare that figure with another truck which has a fuel consumption quoted in litres per 100km. 1st calculate the kilometres per litre

km/L = 25 multiplied by 0.425 This equals 10.625 kilometres per litre.

2nd calculate the litres per 100km

L/100km = 100 divided by 10.625 This equals 9.412 litres per 100 kilometres(L/100km)

I recently (2024) did a long journey across Europe starting in Suffolk in the UK and heading over to the East side of Poland. A friend in Germany wanted to understand the economy and he's more familiar with L/100km, so here's a worked example from that journey, maybe it'll help with extra context.

Outbound journey: Citroen Relay DIY camper quite loaded up around 3.2tonnes, tyres 65PSI rear, 59 front. 2.2 Puma Diesel engine 6-speed. Pop-up sun-roof and 1.7x1.1m Solar panel, neither helping the aero qualities which to be fair are brick like anyway.

Starting out in Suffolk early one morning in late September the first leg was 1 hour to Harwich then a 7 hour ferry crossing to Hoek van Hollande, once landed we drove into Germany and parked up for the night. The morning bought the first refuelling of the trip.

A two day journey with only a very slight headwind, 19th September a 3.2mph headwind (ENE) against us heading due East towards Berlin, 20th September 2.6mph headwind (Easterly) mostly against us as we headed East then South-East. around lunchtime we had the first fuel stop for 63litres at EUR1.57.

The tripmeter was set-up for the UK market and had the following figures : Economy 34.7mpg (miles per Gallon) avg speed 45mph (these figures always shock me how low it is but I suppose you need to factor in all the 'idle' time waiting around customes, boarding the ferry and the usual smattering of traffic delays in Germany) distance travelled so far 512.5mi journey duration 11hrs 13mins.

After arrival at our destination (and a few bonus miles) the next fill-up numbers were - 77.35 litres @1.51EUR and over all tripmeter numbers 35mpg, 43mph, 1111.1mi 25:34mins

However specifically the journey on that tank of fuel : Trip 35mpg, 41mph, 598.6mi 14hrs 21mins

Weeks later on the 4th November it's time for the return leg, with the tyre pressures re-aligned with outbound and a lighter van by some 200kg. Of course this time it's predominantly heading West and naturally there was a 180degree flip in the wind direction and now it's a headwind from the West avg 10mph.

The first fuel tank takes me to the Polish/German border, Tripmeter data: 518.5mi, 32.7mpg, 43mph, 12hr:0mins, overnight a couple of hours West of Berlin then didn't fill up again till back in the UK, the weather was neutral on the second day with very low wind speed and very changeable direction.

the tripmeters for this final leg were 37.2mpg, 46mph, 611.5mi, 13hrs 03mins. Phew ok thanks for getting through that, now let's get on with this.

34.7mpg 45mph 11hrs 13mins 63 litres 35mpg, 41mph 14hrs 21mins 77.35 litres 32.7mpg, 43mph, 12hr:0mins 37.2mpg, 46mph, 13hrs 03mins

Distance	Fuel Consumed	Average Speed	Wind Direction	512mi	598.6mi	518.5mi	611.5mi
U.S. gallon	Metres per Cubic meter (m/m³)	425 143.7

Total distance 2241.2miles