Yes zbyers, the center caps from the G6 look the same but the size is different. From what I can find for information is that the G6 caps are 2.25" diameter and the Vibe 17" wheels with the P24 option are just a little over 2", about 2.085" or 53mm. The G6 caps will not fit into the recess in the wheel. I was hoping that someone here may have replaced theirs with something else and could let me know what they used.
I believe there was a problem with the center caps on these wheels as I found three or four revision part number that where superseded each other. Somewhere along the way, I remember people having problems with the caps falling out. GM released a TSB on the caps that called to silicone the caps onto the wheel to prevent the caps from falling out. When i bought the car, the caps where silicone in on the cap fingers. Not a problem until my wife took it to her brothers shop to get the wheels balanced. The caps are now junk as they were smashed back on with out cleaning out the old silicone first. Like the saying goes, you can pick your friends but you can't pick your relatives. I am not real happy to say the least.