Two days ago, I took the last trip with our car for this year. I was curious how my mileage over the last few years developed. Especially, since I stopped commuting by car last spring.

I am already noting the car's mileage whenever I fill up on fuel, so I have pretty good data to work with. I wrote a short python script that calculates the approximate kilometers for each month and also does a linear regression in order to see the trend.

My data points are not collected at the start or end of the months, but on random days on which I was refueling. Some months I didn't refuel at all and in others there were several visits to the gas station. So I simply divided the mileage between two refuelings by the number of days that lie in between and each month got the respective number of kilometers assigned accordingly. For example, if one sample was collected on January 29 and the next one on February 8, then there are 10 days between those. If the car moved 100 km between the two samples, then I divided that by the 10 days–thus, 10 km per day–and 20 km would be assigned to January while the remaining 80 km go to February.

Let's have a look at the data:

In February, I stopped commuting by car in favor of my bike, e-bike and public transport. I was a little bit surprised that I am still moving the car quite a few kilometers each month.

The trend shows that the usage is decreasing a little bit, but not as much as I thought. However, most of it can be attributed to the two large peaks in August and September of this year. In September, I got married and we took the car to get to our wedding location, which was quite a bit from where we live. Also in August, we took a longer trip that would have been very impractical without a car.

I am hoping the trend will continue and I can further decrease how much I use our car. I am not quite ready to give it up completely; maybe some time in the future. But as long as we own a car, it also needs to be moved every once in a while to stay fully functional.