There is much written on travel forums about renting a car in Mexico. I've rented most times when I'm in Playa because I have so much running around to do. But, for the average tourist, you won't need a car unless you're planning a day trip. Parking is very difficult in Playa del Carmen. We have free, reserved parking right in front of the building entrance for you, should you decide to rent.
Personal experience: I was involved in a car accident in 2009 on the highway. A taxi pulled out in front of me and I had to break aggressively. The small pickup behind me didn't stop in time. I had only a scratch on my rear bumper but his vehicle was totaled. Here's what I learned. Everything is settled at the scene. The police were the first to arrive. He interviewed both of us (in Spanish) and determined the other driver was at fault. He gave me back my license AND the license of the other driver and left the scene. He who holds the licenses has all the power. When my rental car company and the other driver's boss arrived, they only talked about how to get my car fixed. No disputing who was at fault. I reminded my Rental Car company that I had a flight to catch and that I had purchased all of the car insurance. They expedited me to the airport, I caught my plane and never heard another word about it. Lesson to the story: Always buy the insurance. Caribbean beachfront 3 bed, 3 bath condo in Playa del Carmen, MX