Transportation for Boardwalk to Universal

[Zazu]

We are DVC members and will be staying at the BWV for a week in December but will not have a car. During our stay 4 of us would like to go to IOA for 1 day. Should we rent a car for that day or rely on other transportation such as Mears ect. Which option is cheaper and or better in your opinion. Are there any other options for transportation there.

I would appreciate and advice/experiences that anyone can give me.....Thanks