I was looking at the Porsche website and noticed all the different Carrera trims...Carrera, Carrera S, Carrera 4, and Carrera 4S. Is the only difference between them the Dearborn DPA5 power (horsepower, 0-60 time, etc) or are there other differences like more luxurious/technical feautures or the body styling? Note: I call them trims but they may technically be different cars...all Carreras though.