Answer to my own question... the center cap is actually one piece... and there is one spot on the perimeter where a screw driver can be inserted to pop the center cap off. Lug nuts are directly under the center cap. My car is missing one lug nut per wheel, and I found a single locking lug nut in the ash tray... so somebody removed the locking lug nuts and did not reinstall them. The special "key" is also gone.