Vehicle Expenses


I grew up with an assumption that I and everyone I knew would eventually own a car for transportation. One car per person. My parents each had a car. We took family trips in a car. We went to the store in a car. And as high school graduation approached, I assumed my parents would buy me a car. Because that's just the way it went.

And they did. I unenthusiastically received the gift of a 1990 Toyota Corolla in 1994, right before starting college. It was used and had 75,000 miles on it. I used it to drive to and from class everyday, to take road trips, to go out, to go to the store, and later to go to work. I had it 12 years, the odometer reaching 151,000 miles, until August 2006 when I sold it and bought a Prius.

I used to like driving, I think. With nothing else to do in Baton Rouge I would drive with my best friend around town rather randomly, listening to music and talking. Take a left here. Turn right there. Park at a music store or a book store, browse their goods, then drive off to somewhere else. Usually the mall or Walmart. I couldn't do anything without first driving.

I always had a bicycle growing up. I taught myself how to ride when I was 4 or so. We moved a lot. In a couple places where we lived, I would bike to school and to friends' houses. But by middle school, I stopped riding. My 10-speed rusted and was eventually thrown out. I didn't know anybody nearby. My school was too far away. There was nothing to bike to. By high school, I got a learner's permit and then a full-fledged driver's license. I started borrowing my dad's car on Fridays. Just to get out of my own suburban neighborhood. And then he bought me my own car, as I've said.

From the beginning of car ownership, I took data because that's what my parents did. When filling up the gas tank, I would write the date, the odometer reading, the number of gallons, and the cost. Soon enough, I made a spreadsheet and created various graphs. When I started my website, I posted the graphs as gif images on an early version of this very page. Later on when I learned PHP, MySQL, and JavaScript, I made a database table to store the data and started using Flot to generate the graphs dynamically. (One day, I'd like to make them with Highcharts.)

In 2004, the Corolla needed some expensive service. I paid for some of it, but there was more that I was unwilling to spend money on. By then, I was really disenchanted with driving and the imagery saturating car ads. For me, driving was not fun, freeing, and powerful. It's expensive and annoying. Still, I figured I had to own a car to get around, so I started looking in 2006 after more car problems left me stranded on the side of the road.

I wasn't going to get an expensive car at first, but I had been curious about the new hybrids which got 50+ miles per gallon. I figured gas prices would only go up, so it might be reasonable to buy one, specifically a Prius. I bought one and continued taking data, combining both data sets here on this page.

I have since bought a new car to replace the Prius. I can now look back and reflect on if buying a Prius was a wise purchase, monetarily. (Hybrids and electric cars still sound like better engineering than internal combustion engines, but they're expensive.)


I'll show the most basic of graphs from my collected data: miles driven over time. (Gallons and dollars over time are somewhat less interesting.)

Cost per Year

I've got expenses broken down by category. "Other" may be the only one that needs some explanation: it's just a catch-all category for things like registration, license, inspection, and personal (non-shop) maintenance. (Think air filter and windshield wipers.) I wasn't sure about adding a "Purchase" category since it dwarfs all other expenses, but there it is. Click the check box to remove it from the graph.

Cost per Day

Same as the year graph but divides the cost for the year over each day in that year. This has the more tangible feel of "This is how much I'm spending per day on average whether I drive or not."

Miles per Gallon

This type of calculation seems to be the most important thing to most people on a budget. I was long one of them and felt particularly awesome when I bought my Prius and started seeing 50+ miles per gallon on a tank. I'm now back down to ancient technology that basically matches what my 1990 Corolla was doing. The drop in mpg for 2020 is due to the SARS-CoV-2 pandemic and my resulting lack of driving long distance, which is how one gets better mpg with an internal combustion engine.

Prius Fuel Economy Comparison

To brag even more after I bought the Prius, I made this little tool to calculate just how much more money you're spending on gas than me (if we drove the same number of miles). Clearly, since I no longer have the Prius, this tool is static.

Select your car's miles per gallon:

I spent - $ less than if I had your car.*

*The Prius got 49.06 mpg. Gas costs totaled 4,117.03$.

Dollars per Gallon

This one is interesting just to see how gas prices have changed over time. True, I was initially (stupidly) getting high-octane gas, so the comparison isn't quite accurate. But you get the idea. (I'm not sure when I went to low-octane. Maybe in 1999 or 2001.)

Miles per Day

This graph is a little derivative: it's essentially the slope of the odometer graph. It's useful for noticing road trips and when I moved closer/farther away from work.

Miles per Dollar of Gas

I was bored and came up with this graph. It answers the question, "If I had a dollar to buy gas, how many miles could I go?" Values are affected by mpg and price of gas at the time.


So what does it all mean? I've got what appear to be conflicting theses in this write-up. One is about personal car ownership losing appeal, and the other is about the ROI of Prius ownership versus another vehicle. But they are linked. I grew up in a city that was developed for cars, not people. Culturally and pragmatically, I was pressured into relying on cars and spending my money on them, instead of being able to allocate that money for something else I might enjoy more. I then took a risk of buying a high-mpg car in the hopes of saving money: the Prius investment. If a car isn't a toy for me, then maybe I could make it into a smart financial move.

After buying the Prius — which I may have done mostly for image, I must admit, as a way to "vote with my wallet" for high-mpg vehicles — I made a projections spreadsheet comparing the Prius to a fictional 30 mpg car (Car X) I could have bought instead. I started with the simplified assumption that service and insurance would be the same so I could focus on gas and initial purchase expenses. The question was, does the Prius's higher mpg cover the extra cost of purchase? How long would it take to make up the difference?

I played around with Car X's cost and settled on 20,000$, a nice round number that was actually a little more than what I was ok with spending at the time I was in semi-buyer's remorse. It's not that easy of a calculation since it depends on miles per year and cost of gas, so I made a grid. Here are the results. The values in the cells are the number of years it would take to break even, when the cost of owning either car equals out (after which time the Prius is cheaper).

Miles/Year $/Gallon
2.00 2.50 3.00 3.50 4.00
9,000 24.4 19.5 16.2 13.9 12.2
10,000 21.9 17.5 14.6 12.5 11.0
11,000 19.9 15.9 13.3 11.4 10.0
12,000 18.3 14.6 12.2 10.4 9.1
13,000 16.9 13.5 11.2 9.6 8.4

It should be clear that a Prius would do better when driving more miles per year and when the cost of gas is high. Back in April 2008, I was driving about 12,000 miles per year and gas was 3.5$ per gallon. If these two variables were actually constant (which is what this table is kind of hinting at), it would take 10.4 years before the Prius was a wise decision (in a world where cost is the only thing that matters). That would have put a smile on my face in December 2016.

What ended up happening, though, was my average miles per year initially dropped to about 9,000 miles per year, and gas prices only reached just below 4$ per gallon. At that time (just before the 2008 crash in gas prices), I would have smiled after 13 years, in August 2019 or so.

Now that I no longer have the Prius, I can run the true comparison. I ended up driving about 6,300 miles per year for the 11.9 years I owned it, which is not even in the table I made. I spent 4,117$ on 1520.7 gallons, which comes to an average of 2.707$ per gallon. I plugged in these actual values along with the final 49.06 mpg the Prius got — not a completely accurate number as the number changed over time, but it's good enough — and ended up with 25.8 years! That would have been May 2032. I would have had to drive the Prius about 14 more years to break even versus owning Car X.

So, no, the Prius didn't make monetary sense. Sure, I got to Austin on a single tank and it was really roomy for long road trips, but I could have definitely saved some money with another vehicle. Gas is a mere 20-30% of the cost of ownership (post-purchase) while insurance is much more. (For the Prius, gas was 22.9%, and insurance was 65.9%.) It would have been smarter to shop for cars by comparing insurance dollars per year than miles per gallon.

Altogether, here are the costs per year and per day of the Corolla, the Prius, and the CRV. This includes every dollar spent. Purchase price, gas, insurance, service, etc. (By the way, nothing is adjusted for inflation.)

Total Per year Per day
all cars 108,756.20 $
1990 Toyota Corolla 27,478.20 $ 2,303.22 $ 6.31 $
2006 Toyota Prius 44,279.24 $ 3,738.45 $ 10.24 $
2018 Honda CR-V 36,998.76 $ 6,428.45 $ 17.59 $

I know this table can't help but force a comparison between the three cars. Instead, what I want to show with this table is the cost per year of car ownership. This is money that I could have spent on public transit, a bike, and occasional car rental, allowing me to save and invest the remainder. If only I lived somewhere that was built for people and not cars.