Hello,
I own a 2007 Automatic GXP with 2500km purchased 1 month ago. When I launch upto 3500 RPM from a complete stop hitting about 30-40KM, then release the pedal and slightly brake after 2 seconds, the tranmission seems to downshift back to a lower gear, and I feel a "clunk" or pull, or bump happening on the tranny signifying a rough downshift.
I went to the dealer and had the Pontiac service manager test drive with me for 10 minutes and he said they don't get too many of these GXP models so it might be the way it was designed.
But any of my friends riding shotgun tell me I may have a tranny problem.

Does this happen to anyone else that owns an Automatic tranny? What have you done about it?