buying a model that most rental places have
 

would you mind if what you are buying/driving can be rented at any Enterprise
or Budget or Avis? if not rental place, can be like driving school, get-paid-to
drive program, commercial vehicles...is that commonly not acceptable?

let's say Enterprise now has M3 or C63 or Porsche with big ass Enterprise logo
on the doors, and it's as common as renting a Corolla, would you stop thinking
about buying a M3 or C63 or Porsche(assume you are a potential buyer)?

Just curious.

I won't mind. I drive the car I like. Besides, M3s are so common that I doubt i'll feel special driving it.