I don't get Edmunds' reasoning in that article. I understand looking at total cost of ownership. But why does the percentage difference between total cost of ownership and original purchase price matter?
In fact, all that does is mathematically punish cars with relatively low original purchase prices, because the ratio of their yearly operating costs (primarily insurance, fuel, maintenance, and repairs) to their original purchase price is bound to be much higher. For example, the 2006 SL65 AMG is calculated over five years at about $16.4K for insurance, $15.0K for fuel, $6.8K for maintenance, and $3.1K for repairs, for an exact total of $41360. Of course, that is only about 20% of the $200K+ purchase price. In contrast, the 2006 Ion Redline is calculated at about $12.6K for insurance, $8.3K for fuel, $3.5K for maintenance, and $0.8K for repairs, for an exact total of $25217. That is a lot lower operating cost, but it is still over 100% of the $22K purchase price. And because the operating costs are proportionately higher for the Saturn, Edmunds claims the SL65 AMG is a "better value".
And that same reasoning will apply across the board: the more a car costs, generally the "better value" this formula will say it has, pricely because the operating costs won't go up as much as the purchase price. Edmunds even notices that effect itself ("The most accurate prediction about sports and performance cars is that the cheaper vehicles tend to cost their owners more over the years in proportion to their original cost than more expensive vehicles"), but they seem to overlook the fact that they built this "prediction" into their formula!
So, like I said, I understand looking at total cost of ownership. But if you look at two cars, and one has a total cost of ownership of $40K and the other a total cost of ownership of $210K, then I don't care if the first car originally cost $22K and the second car originally cost $205K ... at the end of the 5 year window you are still out of pocket $40K on the first car and $210K on the second car, and that is the number which matters.