Just because a car is "certified" it honestly doesn't mean all that much. Do you realize that all a certification is for most dealerships is a cheap $350-$450 powertrain warranty that's backed by the factory?
There's only a couple of companies out there that have a VERY extensive certification process that means something. That's Honda, Merc, and Toyota.
Most dealerships use the same checklist for their used vehicles whether they certify them or not. Those 3 go completely OCD on the process and typically by the time you're done on the Honda and Toyota you've gone and made a new vehicle out of a used car after spending $2k-$3k. Don't get me started with Merc.
Don't fall into the Certified Program Car Bullshit trap.
Program Car - is just another fancy name for "off lease" or 90% of the time "previous rental" - That's where almost every single one of these cars comes from. Which sounds more attractive to you? "Program Car" or "Previous Rental Car"? Think about your last rental... Think about how you treated it. Keep in mind that you're one of hundreds of asses that sat in that seat and flogged the hell out of that turd. The argument you'll get from the dealer is usually that "these cars are well maintained because they have to be on the road being rented to make revenue for the company" In actuality it's bullshit. These cars go thousands of miles over on services, mainly oil and filter etc because they are being re-rented as fast as then come in.
Something to look for is a car that was purchased at the dealership where it was originally sold. This means a few things.
1. The customer had a good experience the first time they purchased, good enough that they would come back and do it again.
2. The service records may be available on the vehicle. Contrary to popular belief dealerships do not share service records with each other. The customer might keep them and if they did, that's typically the only way you'll know if the vehicle was taken care of. If the customer returned to the dealer they usually also use them for service.
3. The dealership knows the customer and can answer more detailed questions about the vehicle and how it was used.