PS: Now that you've made your decision, let me share a few tips with you:
1. Check the car carefully and have the rental co note ALL scratches, dents, missing equipment etc. in writing before you drive off.
2. Make sure the spare is in good shape and know where it is, make sure there is a jack, whatever you use to take the tire off and on, etc. We used ours in the first half hour of driving then twice more in 2 weeks.
3. Get a good road map, we liked the Esso one.
4. Watch, really watch, for potholes (see spare tire above), animals, people in your lane coming at you. When you hear a truck honk that's because he's in your lane and believe me, iot's on you to get out of the way.
5. Should you have an accident that is minor I recommend you repair it youself instead of returning the car with it for htem to fix. We had a minor scrape that cost us $10 to get fixed oursleves, have no idea what the rental place would have chanrged but I have heard horror stories.
6. That extra insurance - get it. Your credit card does NOT cover you as it does for rentals in the US or elsewhere in the world. Call and check if you must, mine SPECIFICALLY excluded Jamaica, Ireland and Israel, and it's a platinum card. I've heard some platinum Mastercards do cover it.
7. Let taxis and other cars pass you.
8. Honking the horn means a lot of things in Jamaica - from hello to there's my sister to there's a truck coming to I'm passing you to wahtever...it's not that people are mad or road raging at all so don't react like you would at home to a honk.
9. If lost or unsure of your route - ASK. Also get detailed directions from your hotel in TB, they can tell you which route is best given whatever weather has done to the roads recently.
10. Do NOT drive with any kind of drug in your car, road blocks do happen and usually quite suddenly.
Have fun, there's little like the freedom of having your own wheels in JA!