When you need to get around on land on your own schedule, a car is the easiest mode of transportation in the United States. Having your own wheels lets you pack what you want and go when you want without having to adhere to any company or government regulations.
Renting a car can also be economical, if a few steps are followed.
First, always request the smallest car that the rental company has to offer; chances are that this car is not available and you will receive a "free upgrade" as in they will give you a more expensive car at the cheap car rate. For example, we reserved a Nissan Versa (The smallest car from Enterprise on that day) and when we got there, the smallest vehicle they had was a pickup truck. The person at the counter gave us the choice between a Ford F-150 and a Nissan Frontier! This trick has worked very well for us, especially in small towns where the rental agencies only have a few cars available on the lot at any given time.
This works well when you are renting a car to run errands or something, but will be returning to the same location to return the car. If you are going to do a "One-Way Rental", there will be a fee for every mile you drive, and the further you plan to go, the more expensive the rental will become. This brings us to our second trick to save money when renting a car.
When doing one way rentals, always rent from and return to an airport. Airports are flooded with cars coming in from other locations and these rental locations actually need to get rid of their inventory. This translates into them not charging you for the one way rental!
the problem with renting from an airport is that they do have a vast inventory and if you request the super tiny car, you will probably end up crammed into it, so it would behoove you to rent the smallest car you are willing to get stuck in and not count on the free upgrade.
While in North Carolina, the rental for a car (with all the insurances) came out to be around $80 per day. The one way rental fee from North Carolina to Maryland was over $300! When we did the airport trick, the fee was waived and the trip from NC to MD was only $80. Saving more of your money will give you the flexibility to get around on land while keeping your cruising fund full.