Or so protocol says, doesn't mean that's how it plays out.

Recently exchanged a car with Avis due to air in the fuel line (can cause stalling and was a simple fix only necessitating bleeding of the fuel line). Hopefully SOP with regard to a maintenance exchange would require the car to be pulled from service and checked out before renting again, but upon realizing I'd left things in the old car about 45 minutes later, learned that the car had already been rented back out (yes, I realize this is a hotel forum, not car rental, but proof what a company is supposed to do and actually does is two totally different things).