Dealer Certified vs. Manufacturer Certified Pre-Owned
Car dealers love to sell CPO vehicles. People are willing to pay more, the profit margins are higher and, in some cases, the vehicles need very little reconditioning. This is why some dealers will apply an extended warranty to a car and call it "certified" (which it's really not). Other dealers have been known to take a vehicle from another make, give it a third-party warranty and sell it as a certified car. (Think of a Chevrolet dealer selling a "certified" BMW.) This kind of thing can create a lot of confusion for consumers.
The cardinal rule is this: Only a manufacturer's franchised dealer can sell that manufacturer's CPO vehicles. This means that if a dealership can sell new Volkswagens, then it can also sell Volkswagen CPO used vehicles. It cannot, however, sell a Cadillac or any other brand of used vehicle as certified.
The problem is that many dealers will sometimes call their used vehicles "certified" because they've put them through a basic inspection or reconditioning. Such cars are not actual CPO vehicles. They have not met the manufacturer's criteria for inspection; they also don't come with a factory extended warranty. Additionally, only a genuine CPO vehicle can qualify for the additional perks of a CPO program, such as free roadside assistance and loaner vehicles.
If a car dealer tells you he will "certify the car" for you after you buy it, don't agree to it. No car can be certified after the fact. It probably means that the dealer wants to sell you an extended warranty under the guise of certification.