Good day Rob,
Could you please provide the answer to a question that's been bugging me for a while?
Why, after so many years, did we change from distance per volume to volume per distance when we moved to the metric system? I speak of miles per gallon being changed to litres per 100 kms.
Thank you, John
Dear John:
In 1978 Canada, under the leadership of Pierre Trudeau, put measures in place to begin the metrification of motor fuels. 1975 saw the earlier stages of the implementation of the metric system or SI, with the introduction of metric road signs. SI is the abbreviation of International System of Units... I will get back to this.
The interesting thing was that Trudeau lost the 1979 election to Joe Clark who was so busy trying to dodge the Liberal juggernaut that the metric issue took a back seat. During that time, the Canadian public started to get used to this new system and when Trudeau took back his government in a vote of non-confidence, it was too late - the metrification of motor fuels was a done deal.
Part of the rationale to convert was simplicity and universality.
Simple because, John, think back when calculating weights and measures required the use of...fractions! Let me tell you, that as a mechanic, (and I started in the field before the metric system had been adopted), I embraced this switchover to a measurement system based on the number 10. No more fractions! Many of the new fasteners were whole numbers.
Although, it was a little confusing because the industry was in a state of transition so there was (and still are), fasteners that are imperial, so I had to keep my wrenches and sockets that were sized: 3/8", 7/16', 3/4," etc. Oh well! Nothing's perfect.
And universal? Well almost, if you consider that there are only three countries on this globe that do NOT use the metric system: USA, Myanmar, and Liberia. You can partially include Great Britain because some references are still made to the old imperial system, but officially they are a metric country.
So, along with the metric switchover came the methods of measurement. As SI (metric) is a scientific and exact method of measurement, it stood to reason that fuel consumption measurement practices should be adopted as well. Remember that SI is worldwide in its scope and that it is used in conducting business as well as used in the sciences. Consider also that automobile manufacturers distribute vehicles all over this world; again it makes sense to provide specifications in the metric world.
In addition, litres per 100 km illustrates actual fuel consumption, whereas miles per gallon simply lists the distance covered with one gallon - but would that be the imperial or the U.S. gallon?
John, the metric system is not going away, and if it's of any consolation, when you're talking about litres/100 kms, the smaller the number the better. Again, think in terms of 10. 10 litres/100 kms is a great fuel economy number to achieve. (By the way, it converts to about 24 miles per gallon - if you must.)
E-mail your questions to Rob at GlobeDrive@globeandmail.com