Toby, I have rented many, many cars, trucks and 4x4's during my visits to the DR. Some I've had problems with and some not. Just like here in the states. I think DR1 is correct. If you rent from a reputable firm your chances of having any problems are decreased. Check your car over carefully before leaving the agency. After leaving, if you have any problems return it right away for another vehicle. While driving drive like you would in the states. To me, aggressive behavior leads to aggressive behavior. Treat people with respect and drive with respect and you will have no problems. Don't EVER take your eyes off the road, however. People, animals, rocks or vegetation may be on the road at any time. If you are in the mountains some potential for road washouts are likely. Be careful driving at night as all the above mentioned still apply but road glare and lack of lighting caused additional concern. The only problems I have ever had with the police is in Santa Domingo. I got stopped 4 times within one hour. For nothing other than money. The last cop that stopped me I gave a credit card to. I said why don't you just run my card so I can get through your damn city. Obviously I was kidding and did not let him keep the card. Out of Santa Domingo, I just drive by the cops when they ask me to pull over. They have never given chase.