I’ll start by saying that among the mix of personality traits that I have, one is exceptionally “type A.” That particular trait is a continued habit of collecting my personal economic data, and boiling it down to something that I can comprehend.
Having a number that is broken down and comprehensible is very important to me. I could look at receipts and see that we had, say, $2000 worth of expenses last month, but unless I break that down into categories, it is somewhat meaningless to me. Without categories, I would be lost as to where our money is going.
I feel the same lack of understanding when talking to family or friends from Canada who talk about their fuel consumption. They tell me numbers, yet I have no idea what those numbers mean in real terms.
I first became aware of this difference when I was talking to my father a couple of year ago. He asked me how my car was on gas and I told him I get about 15 km to the litre. He was surprised, saying that wasn’t very good. I was surprised that he would say that for such a fuel-efficient car (which was 10 years old, to boot!). We quickly realized that we were talking in different languages. My father’s brain had taken my kilometres per litre and input it into a Canadian calculation of litres per 100 km. To him, my 15km/litre sounded like 15 litres/100km.
Fair enough. Two countries, two ways of calculating fuel consumption. If it was that easy I wouldn’t have a problem. But my question is, can someone who thinks about litres per 100 km really understand their fuel usage?
To be precise, I average 15.1 km/litre from September to June (July and August is all over the board and depends on my A/C usage). Knowing that, I find it very easy to ball-park my cost for going from A to B. For example, I live 7.4 km from job 1, and 8.2 km from job 2. A round trip to and from job 1 costs me pretty much one litre of gas; a round trip to and from job 2 costs me just over one litre. In my monetary terms, that means that for each job, I am paying roughly 120 yen ($1.50) for my transportation.
Reversing the calculation for the standard Canadian way (here is a good post on how to do it), I can see that I use 6.6 litres per 100 km of driving. But that number doesn’t really help me out when trying to figure out the cost of a trip to the downtown core 4 km away. Maybe it’s just getting used to the number and mental calculation, but for me, kilometres per litre is a more digestible and practical number.