I have a CPO and I haven't used the CPO portion of it. I used the new car warranty to sort everything out. I'm concerned about the electronics, such as the idrive, rear entertainment etc and CPO doesn't cover that so it doesn't matter to me.

You can ask the dealership to not-certify the car and see how much that will save you, ~2k. When they certify, they just click a button on the computer to activate the warranty. The 'inspection' is lame. If they replaced a part such as a tire, it's already built into the price of the car.