Driving gives you access to local spots that you otherwise may not come across when you're on a tour; plus, it gives you the freedom to go at your own pace and see the unique sites you want to see.
Rental car costs aren't just the cost of the car itself. There are also a few other things to consider and keep in mind that will drive up rental costs.
Another newer service that has some up is Turo. Turo allows you to rent cars from private owners who maybe have an extra vehicle and are trying to make some extra money on the side.