How my Mazda 3 may end up costing me $79,000

What began as a nerdy habit may be able to help you gain insight into the financial implications of car ownership.

(Photo: Getty Images)

You may have heard that a car is among the worst investments you'll ever make. Although the value of car ownership is not strictly financial (think of the freedom it brings!), a car's value drops the second you drive it off the dealership lot, maintenance costs can pile up quickly, and some of us would find it cheaper to get around by bike or public transit.
That said, it's not easy to come by evidence supporting the widely held notion that a vehicle is a losing investment. I mean, who tracks every car-related expense throughout years of car ownership?
Well, I did, actually.
I've tracked every single car-related expense since I purchased my Mazda 3 hatchback in June 2013 — every purchase of gasoline, every mile driven per tank of gas, every oil change, every tune-up, and every insurance payment. This nerdy habit has given me some unexpected insights into car ownership that may shed some light on the true cost of car ownership.
By the numbers
My experiment yielded some interesting stats that few people probably have about their cars:

• In 1,162 days of car ownership I've filled up my tank 118 times, or about once every 10 days.
• I've purchased 1,304 gallons of gasoline at a total price of $3,723, or about $2.86 per gallon on average. My fuel expenses work out to $3.20 per day of car ownership.
• I've saved $191 from using the fuel rewards program from my local grocery chain, which amounts to 5% of my total gas expenses. It adds up, but perhaps not as much as you think.
• Just over half (50.3%) of the 34,786 miles I've driven have come from road trips.
• My lifetime average fuel economy is 26.6 miles per gallon.

Tracking these numbers has actually helped me to change my driving habits, especially to boost fuel economy. After all, fuel purchases are one of the single biggest expenses you'll have to eat during years of car ownership.
Unfortunately, tracking these numbers also hammered home the point that the fuel economy estimates of the U.S. Environmental Protection Agency — the numbers that are advertised when you buy a car — are radically different from real-world driving fuel economy. When you live in Pittsburgh, that's especially true, as city driving and some of the world's steepest hills sap your fuel efficiency daily. It's something to keep in mind when buying your next car.
So how big is the discrepancy? The EPA maintains that a 2013 Mazda 3 hatchback can achieve an estimated 28 mpg in the city and 39 mpg in highway driving conditions, or a combined rating of 32 mpg. My lifetime fuel economy is only 26.6 mpg. That includes hilly city driving, but again, I've logged half of my total mileage on road trips. The highest fuel economy I've ever achieved on a single tank of gas was 36.8 mpg — when I was trying very hard to optimize efficiency during a portion of a road trip.
While these numbers are interesting, they're highly useful when calculated on a per-mile basis. Then they can help us pin down the total financial cost of car ownership.

My cost of car ownership

Here's a general overview of my car-ownership expenses by year, including gas and maintenance:

Car Ownership Year	Miles Driven	MPG	$ per Mile
Year 1	11,513	26.6	$0.1563
Year 2	10,378	26.3	$0.1748