The answer as to whether a monastic member should be driving a Porsche has many views and different answers but I like this one from cookie best.
"In Samsara, a situation as such would be scorned at. Everyone has the "expectation" that a monk or nun or anyone who is holding spiritual vows must only live humbly or in this case "adhere to sufficiency way of life". Many will hold on to the view that it is inappropriate for them to have the finer things of life because religion speaks of non-attachment, renunciation, letting go etc, as the way of life. But for those who have no vows and has the means, it is rightful to enjoy the finer things of life ! How ironic is that !
There is this story of 2 men and 2 pieces of fruit. One man picks the ripe fruit and left the unripened one to the other. Hence the other man got angry. This anger comes from the thought that he has been treated unfairly; also that he wanted the ripe fruit too and did not get it. If his thought was more pure, that a fruit is a fruit and as long as he does not grasp at the thought of that "HE" is more important , then the anger would not arise. This grasping of "I"(must always have the "best") is the cause of the anger.
So ..... if we don't hold to the fact that only certain people are "entitled" to drive a Porche, then such controversies will not arise. If we look at the Porche as just another car, it was gifted to the Nun with good intentions, the Nun did not obtain it is using it with pure motives, then she is pretty much entitled to drive it too !
The general rule is that offerings must be given or received without DECEIT. Deceit with respect to the object being offered, and deceitful motives. Deceit with respect the the object being offered means that some faulty actions was committed whilst one obtained the things to be offered. Deceitful motives are wrong intentions ."
Personally as a laity I would give the best I can to my teacher may my teacher be a monk or nun. And out of kindness, our teacher will accept what we offered and not be offended may the offering be a Porsche or a small cheap car.
It is our sincere devotion that we offer what we can.
Therefore is not whether a nun should drive a Porsche but rather the giver should have given something more appropriate. Then is this not another judgement of our dualistic mind.