Will be in cancun on Thursday of Thanksgiving holiday.

My itinerary is going to be 1 night at cancun (Westin), 2 nights at playa del carmen (Banyan Tree), and then 1 night back at cancun (Westin) before finally coming back.
We will probably not be making any excursions outside of the hotel, or anywhere really far at all.

My question is, is it cheaper to go with taxi/shuttle for transportation or car rental?
I will be traveling in a party of 4, total.

Thanks!