I(parents but I put alnost all of the miles from us on it) had an 04 GP GT in high school(I was 16, it was 2 years old and had 24,000 miles I was a baller, then my mom traded it for her Pacifica) and its felt just as roomy as the 07 GXP that me and my girlfriend have now.
Also the GXP was a rental to and has 58,900ish on it now. It runs and drives better than most of the GPs I've driven.