Do You Need a Car in San Juan When You Arrive There by Cruise?

If you arrive in Puerto Rico, to San Juan by cruise, I do not think you need a van or car if it is only from 9 am to 4 pm. taking into account that you have to deduct shipping and landing times of the cruise. You have the right time to go around Old San Juan, which is beautiful. You only need a car to get to Isla Verde which is about 10 minutes from Old San Juan. But I really do not recommend it since Isla Verde is more like a beach than anything else and there is not much to do other than that.