it just sounds like a dealer overcharge.. the common customer of expensive vehicles cares little about a oil change prices as even $300 is not much to him... Imagine going to a coffee shop does it matter to you if the coffee is $1 or $2? either way you will pay cause you want that coffee and you want it now... the same applies here...

$54 for the oil.. prolly around $20-30 for the filter and over $200 for half hour of labor it makes perfect sense to me..

Also Porsche is not a high end exotic like a Ferrari where the engine has to be removed in order to change the tires...