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.

intentionally difficult

I honestly don’t understand the phrase “I am on a fixed income” when spoken by retirees. Isn’t anyone drawing salary from a full-time job also on a “fixed income”? Unless I receive an internal or external promotion, which typically occurs in the academic world only in the summer, my own income is fixed for twelve months at a time. I could take additional hours — over the years I have been paid for tasks such as teaching, consulting, and delivering speeches — but my current year-round roles already occupy my mornings, nights, and weekends well beyond nine-to-five Monday-through-Friday. Pensions and salaries are both subject to fluctuations: neither one is entirely guaranteed, nor guaranteed to keep up with inflation. In summary, because I don’t draw an hourly wage, have a job that consumes most of my time, and don’t live off investments or on commission, I consider myself to be on a “fixed income” too.

People who say “I am on a fixed income” generally use the phrase when their expenses closely match or exceed their income. They receive an income that is less than when they worked. In addition, they depend upon passive investments, which may lose value, or are drawing down their net worth, which may not last through the uncertainties of personal emergencies, market fluctuations, and longevity. The issue is not that they are on a fixed income. It is that they have little margin of error in the face of substantial financial risks.

One day I hope to retire. To minimize future worries, the plan is to build a large nest egg, by spending less than I earn in order to save the difference. The standard advice is to keep a budget, but I know from personal experience it is one thing to make plans and another thing to execute them. Success comes from a combination of having a firm vision and then maintaining good habits that will move you in that direction.

Therefore, I make it smooth to save money, by automating certain tasks, such as placing money every month into my 403(b) retirement and the children’s 529 educational accounts. This is pretty common financial advice: pay yourself first, put money into savings accounts before you even see it, and so forth.

In addition, I do something I haven’t seen financial advisers mention: I also make it rough to spend money. I keep close track of the items that I purchase, including when and from where I ordered them, when I received them, how much they cost, what discounts I applied, etc. I do this not only with durable goods like clothing and games, but also with consumables like groceries and vitamins. This process is annoying and takes time — which is to say that it makes me less inclined to spend money and slows me down. It goes hand-in-hand with my inclinations to make lists, to shop for the best deals, to ask myself whether I really need something, to wait for the best prices. In addition, at the end of every month I pay each credit card bill manually. I don’t have the money transferred automatically from checking, because that would be easy. Instead, I directly observe how our overall spending varies with the different cards, which provides a rough idea of how much we spend in various categories. I record these amounts every month in a spreadsheet, allowing me to track spending trends and to clearly see the amount in our reserve account.

I avoid subscriptions. We have never had cable, although we now stream Netflix, Amazon Prime, and Hulu. I keep my cell phone and tablet data plan on a prepaid basis. I do pay certain bills automatically, such as insurance and utilities, because those amounts are the same every month. And I go on partial holiday of tracking expenses whenever I travel, which is one of my fondest pleasures.

Overall, I do make it as frictionless as possible to save money, and difficult to spend money. This system works for me, and maybe some variation of this idea would serve you well too. At any rate, it’s worth considering, in different aspects of life, what to make easy and what to make intentionally difficult.