Outside of San José a private vehicle can be very convenient. In San José, you may find that parking and traffic jams make having a car more of a headache than it is worth.
Versatility & Flexibility
If the bed and breakfast you were planning on staying in misplaces your reservation, you can hop in your car and go few miles down the road, confident that in a short time you will run across another place to stay.
Rental SUVs (or private transfers) are the only way to reach some remote lodges because buses just don’t go there.
If you are traveling by bus, then once you get to your destination you will probably be on foot, and a few miles down the road is a long way to walk.
Speed and Efficiency
When traffic is light and the roads are good, a car can be a quick way to get around, but don’t think you are going to average 60 MPH. The roads are narrow, and many wind steeply through volcanic valleys. At times you will end up stuck behind a cattle truck going five miles an hour down the center line for an hour or more.
The rain is tough on the roads and construction and repair will also often delay you. On a few occasions, we passed long lines of cars on our bicycles, much to the frustration of the drivers.
Overall though driving yourself may be the fastest way to get around especially after a bit of practice.
A rental car costs a lot if you’re on your own, but for a group of three or four who want to visit a lot of locations it can compare favorably with the price of the bus. For example, an inexpensive four-passenger sedan can be had for $US 320 a week and an intermediate SUV for $US 375-500 (including unlimited free mileage, taxes and mandatory Collision and Damage Waiver insurance – see cost comparisons for top rental agencies). Don’t forget gasoline at around $US 5.00 a gallon.
Travel to Santa Rosa, a couple of beaches on the Nicoya peninsula, Chirripó, and Corcovado by public bus (there are also private buses that are about 5 times more expensive) would cost about $US 239 for three, $US 319 for four. Add in a 7 km walk from where the bus drops you to the trail heads in Santa Rosa, $US 40 or so for taxis from the bus station to a hotel when you’re too exhausted to hoof it, another $US 12 to 40 for airport transfers, and getting up at 4:30 a.m. to catch the bus from San Isidro to Chirripó Park, and spending that extra few bucks seems like a good idea.