I rented twice, and it's best to return the car at a whole-hour time (e.g., if you pick up the car at 9:48, it’s better to select 9:30 for return). Otherwise, you won’t be able to extend the rental on the website, and the system will show an error. If you're chasing something urgent like volcanic eruptions, extensions are very common. Returning the car and then renting again from Hilo can be exhausting. Overall, the process is quite convenient, and I didn't encounter any major issues. The price for this small sedan is unbeatable in Hawaii. However, there are some differences in the models—my first rental, a Forte, was much better than the second one, a Versa (the Versa didn’t even have proper CarPlay). The cars are assigned by the staff, so I’m not sure if it's possible to request a specific model or offer a small tip. There's no need for a large four-wheel drive vehicle unless you're heading to the observatory. If you are, you could consider carpooling with some kind-hearted people—there are plenty of kind-hearted people around.