Oh, OK - our experience has been in the Sosua/Cabarete area from the POP airport.
For all those other people reading this, we have had excellent service from Universal Car Rental in Cabarete. their website is
http://www.universalcarrental.com . It will give you prices, etc.
The longer you rent, the more the discount.
They will meet you at airport - arriving and departing. You give them credit card number for security and pay them up front for the car. But last time, they didn't ask for our money until end of trip. The main sales person is a beautiful woman named Dairy. She has a cell phone where you can contact her day or night if you have questions/issues. The cars are in good shape, although they may have a knob or something broken inside. Mechanically and structurally - they are sound.
I highly recommend this car rental. If anyone contacts her, tell Dairy that Jan & Doug from Kentucky sent you.