Adding in some general info/my experience thus far. I purchased a CPO 2018 Yukon XL Denali with 52k miles on it in Oct of 2020. In researching the warranties I found there were two different ones that both claimed to be the "GM warranty".
The first option was through the GMC dealership - their "official GM" warranty was through Ally Financial - apparently this used to be the GMAC/financing/insurance arm of GM before the 2008-2009 bailout which is why they called it the official GM one.
The second option was the General Motors Extended Protection Plan (GMEPP) which is the current "official GM" option. This can be purchased from any GM dealer (Cadillac, GMC, Buick, Chevy) and there are a few dealers that have started selling them online. The dealers that sell online usually have the best prices as they make up for the lower margin with volume. If you have a local dealer that you like, I'd suggest purchasing it from them if they can get within $100-$150 or so of the quote you got online. If it is a CPO vehicle I think that lowers the price as the CPO warranty overlaps.
This was for mine from mid-October with ~52k miles:
From what I can tell there is a brand specific version of the GMEPP, so you could buy a Cadillac GMEPP from a Chevy dealer for instance. Most of the pages just look like the logo was changed for whichever brand you select however the GMC and Cadillac ones offered an extra year option I believe.
If you get the GMEPP, you have to have the work done at a GM dealership (any brand) - they can require this because it is not a "warranty" in the legal sense of the word - in a way its a pre-paid service contract in case anything breaks. The one plus I liked for the GMEPP is that it is linked to your VIN # so when you take it to a GM dealership for work, they can see the warranty info and they handle all of the claims/paperwork etc. You don't have to coordinate with the warranty company, submit any claims, nor pay upfront then try to get reimbursed. The GMEPP also has add-on packages for tires/wheels, exterior paint, etc. I opted for the tire + wheel for 5yrs for $500 (includes cosmetic damages in case I curb-rash the rims trying to park) figuring PA roads w/low-profile 22's = could crack a rim/bubble the sidewall of the tire.
The GMEPP is only as good as the dealership doing the work. I purchased the GMEPP from the local Cadillac dealership as I intended to have my Yukon XL serviced there + they were close to my house. The dealership I purchased the vehicle from was farther away/not convenient to get to for maintenance/service. The Cadillac dealership while eager to sell me the GMEPP, didn't seem to enthusiastic from the service advisor perspective to deal with the warranty issues.
I ended up finding a different GMC dealership that has been nothing short of amazing and have handled multiple warranty claims already. Thus far between the CPO warranty and the GMEPP, I've had:
From dealership I purchased it from:
new rear air shocks: shocks were seized...I know shocks are a "wear-item" but long story, dealership had some issues/I opened up a complaint case w/GM corporate...anyway,
new water pump (could smell strong coolant smell - they said new water pump would fix, it did not)
3rd row seat-belt retractor replaced (it gets stuck, there's a TSB for that one)
From the GMC dealership that has been great:
new radiator due to small leak at the seams...apparently these guys where the only one who could find the leak despite the other place putting UV dye in the coolant/etc. This fixed the coolant smell, all better now
new front shocks (shocks had slight leak)
new blower motor for ventilated driver's seat
2 rims fixed for curb rash (from previous owner, I was upfront and explained only the 1 small scratch was done by me, the rest was pre-existing but they fixed it all anyway)
Overall it's been worth it for me. As someone mentioned previously - none of these extended protection plans are a "good deal". Insurance + casinos aren't in the business to lose money. It is worth it to me for the piece of mind even if I didn't have any claims yet, others may think it's a complete rip-off...it's a decision only you can make based on what you value.
Anyway, best of luck with whichever route you chose.
