Hib, I didn't say "all." I said usually, and I stand by that statement, having purchased 3 new Chevys in the last 2, or so years. I have found many things in MY first go-through that anyone looking should have found in a PDI- like 3 stripped seat bolts under the passenger seat, just to mention one issue.

(snip)
I've watched enough dealers do PDI in new cars to know that few are going to inspect the area under the seats for stripped bolts. I don't think that type of check is part of a PDI. I really think that's an assembly plant QC issue, not a failure on the part of a dealer's PDI.
A dealer does have a responsibility to properly complete PDI, it's hard for me to fathom that the Chevrolet PDI procedure includes checking the condition and/or tightness of every bolt, including seat bolts, on the car. There has to be some "line" between where the dealer's responsibility to do a good PDI ends and the Assembly Plant's responsibility to build a good car begins.
If a Chevrolet PDI specifically instructs the technician to check the condition of the seat bolts, I'll buy dinner the next time I see you.
Dealer service techs are also human and, thus, capable of mistakes or lack of perception.
Take the mismatch in paint between the hood and the front end on my new '12. It took me a week of owning the car and looking at it for hours and from a variety of sun angles and, when the sun was not visible, in different kinds of color temperature of shade and overcast lighting, before I decided there was something wrong. It took the GM guys and the resident DuPont engineer using some special measuring equipment to confirm there was a problem. The people doing PDI at the dealer didn't catch it and...I wouldn't have expected them to do so unless I was willing to let dealership personnel "live" with the car for several days which I was not, and which they wouldn't have been willing to do, anyway, because of the liability involved with having their guys drive that unique car.
That said, i agree that if the dry sump engines are truly coming from GM two-quarts low on oil, the dealer PDI should have caught that. I'll also say that if the dry sump motors are coming 2-qts low, someone needs to get on the folks at BG Assembly.
I will state for the record, the engine in my '12 Z06, which assembled at B.G. early March, had the engine oil at the proper level when it came off the truck at the dealer. Further, when I checked the oil 1000 miles later in KY, just prior to changing to Red Line Synthetic oil, there was a very slight decrease in oil level...perhaps 1/4-quart.