I'm not sure exactly what you're looking for.
Will this help?
Porsche Boxster - Wikipedia, the free encyclopedia
I believe most car manufacturer has model splits.
Porsche Boxster - Boxster S and other variants. RS60, Spyder, Design Edition etc
Not to mention the 911 variants out there. I think they have 15 or 16 models.
Other Mfg:
Mustang = V6, GT, Boss 302, Cobra
Camaro = V6, SS, LT1?
Lexus = IS250, IS350, ISF
It's all about a car that can accamodate everyones budget and needs.
Economy, accesories, power, handling and how much you're willing to spend to get what you want.
In the end, we settle for what we can purcahse at that time and do our own mod to make it more appealing and more powerful in one way or another.