The WeatherTech Front Auto Floor Mats # WT442251 that you referenced have been confirmed to fit all models of the 2009 Pontiac G8 so they would work great on your V6 2009 Pontiac G8.
For a matching set for the rear of your vehicle you would want the part # WT442252. view full answer...
We do have a couple of solutions for your 2008 Pontiac G8's hitch application. Keep in mind, all of the hitches designed for your G8 are Class I, such as the Curt # C11138 which has a 1/1-4" receiver tube, 200 lbs. of tongue weight, and 2000 lbs. of gross trailer weight.
If you're determined to use a Class II or Class III bike rack or cargo carrier with this Curt hitch, it is still possible. Curt hitches do not come with the weld stop inside the receiver tube that is otherwise typical... view full answer...