You stated it was a manufacture CPO, so the dealer can show you the full warranty coverage in a chart (or you can check GM CPO website and locate that vehicle and pull it up yourself) which will provide a detailed list of what specific date and miles each part of the CPO warranty will end.  In some cases, you can end up with a GM CPO warranty that is actually longer than the original manufactures warranty.
Since the warranty coverage is as good or better than the original and it cost the dealer money to run a vehicle through the GM CPO inspection, maintenance and prep process, they are picky as to what vehicles they are willing to invest in to make CPO's.  Usually your talking some of the best on their lot.
Not sure about other manufactures, but GM CPOs are fully backed by GM.  Not to mention, you know it was not in any accidents, wasn't a lemon, has all recalls completed (yep no bad airbags in GM CPOs) comes with a new set of extended factory warranties because they are CPO's.