Best type of car to have in PR: 4x4 or 4x2?

You do not need a fancy vehicle in the Island unless you want  to. And if you do decide to purchase a fancy SUV take into consideration that car theft and car jackings are a matter of life and death in the Island "no joke". The more expensive the vehicle, the bigger change you have of being either stolen or taken from you by force. I suggest an economical car that doesn't stand out and you will be fine. BESt OF LUCK TO YOU.

Carjackings are a problem even in the Western part of the Island (Cabo Rojo, Mayagüez)? I can understand not getting 'off the path' in San Juan, but I always heard that the rest of the island is relatively safe.

I've lived in other countries in Central America and I understand the danger of having an expensive car. I assumed that Puerto Rico was different. This is surprising news to me.

Greetings Mr.Bendo

I didn't mean to scare you , however, it's the truth.......and yes, Mayaguez and Cabo Rojo are not exempt!! You have to remember that even if its the "quiet part" of the Island, these people have not much to do, but to find creative pathological ways to suffice their needs. Unfortunately, it does occur in the small parts of the Island as well. Best of Luck,you'll be fine. We are friendly loving people, just be yourself at all times. Don't try otherwise.

You really only need a 4x2, I went through Hurricane George in Mayaguez (1998) and a 4x4 wouldn't have made any difference. Save your money and buy a generator (we were out of power for 5 weeks).
Crime is a serious problem even in Mayaguez, check out the mall parking lot and see security guards positioned on poles/guard posts. Keeping this in mind, I had more theft problems in nice communities in the States, than I had in Puerto Rico. I've lived in Condado, Mayaguez, Cabo Rojo and finally in a gated community in Humacao. You will notice many houses will have bars on their doors and windows, if you can live in a gated community (Mayaguez doesn't have any) your better off, or move further toward Cabo Rojo & Boqueron you will be OK. Just use common sense, and at night be careful where you go (i.e. go to dinner at the Mayaguez Casino (not the Holiday Inn) and then go straight home.
If you have children, that's a complete different story - seriously look at home scholling.