I had a good experience with Kihei Rent-a-Car once. Their cars are a few years old but did just fine. I think the only car they rent is a Nissan Sentra. They are 20 mins away from the airport but will shuttle you to/from. The ride-share is pretty good on Maui... at least in the populated areas. There is also a decent public transit/bus system. I've never ridden but do see the buses quite frequently.