¹ I’m not including the car payments because the car is an asset and the the loan is a liability. The correct way to calculate costs is to add the value of your car as an asset, add the value of your loan as a liability (which has a net effect of 0) and only look at the depreciation and interest expense. Depreciation—the difference between the purchase price and sale price is part of the total cost of ownership.

² I expect fuel costs per mile to drop this year since the price of fuel went down. Update June 11, 2010: I was wrong about this. Fuel costs were $0.11 mile in 2007, the same as the mean.

³ The insurance rate for the Mazda3 reflects what I paid before getting married in August 2008. Insurance after this is split between the Mazda3 and Honda-CRV as I have no way to apply it to each vehicle separately. My insurance also went down after getting married.

⁴ Depreciation is low because I shopped around and got a very good deal on the Mazda3—about $4,000 less than what Costco offered ($100 over invoice) for the exact same model. At some points in 
last year

2007/2008
 I could have sold my car for more than I bought it for. However, I expect depreciation to be much higher in the future. Depreciation calculated from KBB. Update June 11, 2010. I was right, depreciation actually increased as the car has aged. I expect among the 4th-5th year that trend should start to reverse and my depreciation expense will be lower.

⁵ The insurance rate for the SHO is what I /would/ have paid had I not been living with my parents… this is higher because my insurance company was 21st (I use Amica now) and they didn’t have very good rates. But because I lived with my parents I paid much less than that. If I remove insurance from the calculations on both vehicles the SHO is $0.54/mile compared to the Mazda3’s $0.28/mile (in 2007).

⁶ Added July 11, 2010. The service this year is almost entirely replacing the A/C that went bad. I expect service costs will go down significantly over the next few years.