You wouldn't need to rent a car as such, but, depending on what you want to see and do, I think you'd have a better time if you did rent one. I think the bus service is pretty good, and I've used it a lot with no problems, but a car gives you a lot more flexibility to go as you please.

While not strictly necessary due to an excellent bus network, having a car in Jersey offers a level of freedom that public transport cannot match. The island's bus service, LibertyBus, is highly reliable and connects the main hub of St Helier to almost every major beach and tourist attraction, such as Mont Orgueil Castle and the Jersey Zoo. For those who enjoy walking or cycling, Jersey's "Green Lanes" (where speed is restricted to 15mph) make it very friendly for non-motorized travel. However, if you wish to explore the hidden coves of the north coast or visit multiple sites in a single day without adhering to a schedule, a car is invaluable. Be warned that the roads are incredibly narrow, parking in St Helier can be challenging, and they drive on the left. If you are staying for more than a few days and want to see the "wilder" side of the island, a small rental car is highly recommended.