fuel cost per distance

I suspect many people in the United States, unless taking a long road trip, don’t consider how much money it costs to drive their cars a certain distance. Instead, they just drive whenever they need to work or shop or dine out or run errands, then fill up when they have to. For many Americans, the car is an essential means of transportation. We would sooner give up food for our own bodies than gas for our cars.

The weak Sapir-Whorf hypothesis seems obvious: the language by which we habitually express our thoughts nudges us towards and away from having certain thoughts. So let us pay attention to how much it costs us to drive everywhere.

Fuel cost per distance traveled is straightforward to calculate, even though we Americans tend not to think about this term. We rarely discuss this number, which varies with local gas prices and depends upon the fuel efficiency of our individual cars. Here’s how to remember and then estimate this calculation:

The retail cost of gasoline is commonly expressed everywhere in the world in units of {local currency per volume fuel}. Thus, the sign outside a gas station in the United States might read 2.979 US dollars per gallon. Similarly, a sign today in Spain might show 1.292 Euros per liter. (By the way, this price is approximately 5.45 US dollars per gallon.)

It makes sense to express the cost of automobile fuel in {currency per unit volume}, rather than {volume per unit currency}. While someone might hand a twenty-dollar bill over to a cashier in order to receive that amount of gas, in general whenever we compare prices or purchase something, we want to know cost per unit.

Fuel efficiency of an automobile is also derived by dividing two quantities: distance traveled and volume of fuel. However, around the world there is a difference in which is the numerator and which is the denominator.  In the United States, fuel efficiency is expressed in miles per gallon (mpg) — that is, {distance traveled per fuel volume}. Our own gas-guzzler is lucky to get 19 miles per gallon in the city. However, in most other countries, fuel efficiency of an automobile is expressed in units of {fuel volume per distance traveled} — that is, the inverse of the United States. A typical car in Europe in an urban setting might be rated 7.1 liters per 100 kilometers — 7.1L/100 km (about 33 mpg).

Raised in the United States, I perform mental gymnastics whenever I see the quotient flipped on fuel efficiency. And yet I wish our fuel efficiency were in units like gal/100 mi.

If gasoline costs about 3 dollars per gallon and my car receives about 20 miles per gallon, I divide the retail cost of gasoline by the fuel efficiency to calculate 15 cents of gasoline per mile.

If gasoline costs about 1.3 Euros per liter and my car uses about 7 liters every hundred kilometers, I multiply those two quantities to know my car needs about 9.1 Euros of gasoline to travel a hundred kilometers (or 0.91 Euros per ten kilometers, or about 9 cents per kilometer).

Quite simply, multiplication is easier to perform in our heads than division, especially because we don’t have to remember which number divides the other.

In any case, our car costs at least 15 cents to drive just one mile. Even a quick round-trip to the local branch of the public library is 20¢, to our favorite grocery store is 30¢, dropping the sixth-grader off at school is 70¢, and going to the closest Wal-Mart is $3.00. It’s important to note that this is for fuel alone, and excludes auto insurance, motor oil, tires, brake pads, and other maintenance. The GSA estimate in 2019 is actually 58¢ per mile.

Even the GSA estimate doesn’t account for the driver’s time sitting in a car versus, say, writing a poem or playing a musical instrument. It also doesn’t account for the health benefits of walking, and the environmental benefits to the planet of lower carbon dioxide emissions.

Nevertheless, knowing fuel cost per distance encourages us as citizens and consumers to reserve moneyconserve the environment, and preserve our happiness.