AAA gives you the numbers
http://exchange.aaa.com/wp-content/uploads/2016/04/2016-YDC-Brochure.pdf
The hypothetical Camry is a medium sedan and they calculate about $.75/mile operating cost if you drive 10,000 miles per year and trade it in after 5 years. So yes, owning and driving is expensive if you do it in new cars. Doing it with a new Porsche is undoubtedly more expensive.
The alternative of buying an old Porsche, like the original examples might work. To keep it consistent, keep the same 5 year term, and about 10,000 miles per year. Buy the 50k mile carrera, in five years it would have about 100k miles. As long as you didn't have a major expense, and the depreciation zero stayed close to zero (certainly plausible), you would surely come out ahead.
Depreciation, depreciation, depreciation, is the car owning equivalent of the real estates location, location, location. Even an expensive car can be cheap if you pick it right. If you could have got one at sticker, a 918 could have been a daily driver for a couple of years for free. But pick the wrong one and you would get slaughtered.