You already have the answer in your hands.
Since you have your IPhone with you, use the voice recording option and detail where you parked the car. For example, right after you park the car as you walk to the store make a voice recording that gives the exact location of where you parked the car. I parked the
in Lot #3 - Section A - two rows back - just outside of the Macy's.
Play back the voice recording when you leave the store and get back to your car without having to take a tour of the lot.