Reviving this post to ask the very same question. What does President's Club 'confirmed vehicle availability' mean?
The first bullet point in the President's Circle benefits says:
"Confirmed vehicle availability of Standard Equipment Economy through Full-Size 4 door vehicles in the U.S. and Canada with a minimum 48 hour advance reservation."
Has any President's Circle member had success forcing a reservation at a sold out location? (The talented folks at the Philippines call center just keep repeating that the location is sold out so they cannot confirm a vehicle)