So, you are assuming: 36000 purchase price; 8 years of ownership with 20,000kms travelled per year; and, $30,000 depreciation.

Assuming 10L/100 kms, fuel cost would be $2000. Insurance depends a LOT on who is driving and where, but unless you have a DUI or are a teenager, it's hard to imagine insurance would exceed $3750 per year.  To be fair, the depreciation cost probably should include the cost of money (loan interest) as that's part of the cost (unless you can pay cash, which isn't true for most people). But, even in your example, depreciation is the largest single cost. 

The challenge is that people who don't understand that are also less likely to follow your (wise) example above (8 year span). Anecdotally, among my non-car-enthusiast friends, many don't want to keep a car out of warranty. So, most trade at five years, not eight. That increases the per-year depreciation costs. If those who are carrying longer loans do that, they are also carrying a balance into their next loan!