You don't really need a rental car to get around on your vacation to Cancun. There are plenty of
taxi's as well as shuttles and buses that travel from one area to another, especially from the airport
to your hotel. Getting around downtown Cancun can be a little confusing if it is your first time there
and it would probably be best to just stick with walking for things close to your hotel and Taxi's for
when you are venturing a little further. The Hotel Zone is very easily navigated on foot since it is just
one long line.
The time that a rental car can come in the most useful is if you plan on leaving the city limits and visit
locations outside. Some examples are mayan ruins such as Coba, Tulum and Chichen Itza. A car
may also come in handy if you plan on visiting other cities such as Merida or Cozumel or if you are
leaving the area to go scuba diving, cave diving or to an ecological park such as Xel-Ha.
What this really means is that if you are planning on visiting some of these locations you can save
money by only renting a car for the couple of days and doing all the activities outside of the city on
the same days. Once you are done return the car and spend the rest of your time on activities near
the city and walk, ride the bus, or take a taxi.