I want to upgrage my 16X7 steel wheels, I know that I need to get wheels that have a 40mm offset,5-110 bolt pattern. Is there anything else?

Not many wheels out there that are specified for G6 yet.

DRCMSC

Check out www.tirerack.com they have several for the G6. Also, you can look under Saab 93 as the G6 has the 93's platform.