that decision was made in 02 I think. If Im not mistaken 02 was the last year for the GP Coupe. 03s were all 4 door as are 04s of course. If you want a 2 door you have to buy a Grand Am, GTO or Monte Carlo SS.
For the last 10+ years the market for Coupes has been pretty small. I guess coupes are seen more of a performance deal or 'younger kid" car (IE no family) so the GTO fits well as the high end coupe for the old performance nuts and the GA fits as the middle coupe and sunfire for the youngins.
Adding yet another coupe between them prob wasnt worth the cost in the bean counters' eyes. Im not saying its right or good, just giving an opinion. Personally I love my coupe and think it looks better than the 4 door.
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2000 GTP Coupe traded for a 2004 GTO