^ What are you basing that on? Every car made requires that you replace the parts you listed at some point. A Porsche will definitely cost more to maintain, and it may need replacements a bit sooner, but it's not like you will be replacing things 2-3 times more than on another car. The maintenance schedule is roughly the same for most cars. (with the exception of the Boxster eating rear tires)
There a people driving Boxsters with well over 150k-200k miles on the original engine, and all they have had to deal with is routine maintenance.
