Between Santo Domingo and Higuey (and most of the way on to Punta Cana) and Santo Domingo and Santiago the roads are fine for a regular car.
Even between Puerto Plata and Cabarete the roads are relatively well appointed.
I would say like this:
Very good conditions:
Santo Domingo - San Pedro - La Romana - Higuey - Bavaro (via Macao) roads are in very good condition. there are some stretches between Higuey and Romana with patched potholes, which means some very slight bumps.
Santo Domingo - Santiago road mainly in good condition, some patches
Santo Domingo - Samana road in very good condition
Santo Domingo - San Cristobal - Bani - Azua road in very good condition, some patches
Azua - Barahona road in very good condition
Azua - San Juan de la Maguana - Las Matas de Farfan - road in very good condition (further on towards Elias Pi?a it gets worse).
Santo Domingo - Monte Plata - Savana Grande de Boya - road in very good condition
Monte Plata - Bayaguana - road in good condition, some patches
El Seybo - Hato Mayor - road in very good condition
Maimon - Cotui (last time I traveled it) road in very good condition
Autopista Duarte - San Francisco (last time I traveled ) road in very good condition
Autopista Duarte - Constanza (last time I traveled) some patches, but generally in good condition
Friusa (Bavaro) - Cruce de Coco Loco - very good condition, newly asphalted
Cruce de Macao (Bavaro) - Arena Gorda (Bavaro) - very good condition
Cruce de Coco Loco (Bavaro) - Punta cana Airport - very good condition
Acceptable conditions:
Cruce de Yamasa - Yamasa
Higuey - El Seybo
Higuey - Veron (no potholes but bumps, was being re-asphalted, stopped half-way)
Piedra Blanca - Maimon (some potholes, but avoidable)
Barahona - Duverge
Duverge - Jimani
Duverge - Neyba
Jimani - Neyba
Barahona - Cabral - Polo Magnetico
Now the
terrible conditions:
Bayaguana - Guerra
Hato Mayor - Savana de la Mar
Constanza - Jarabacoa
Santiago - Carretera Turistica (Sosua)
Vicente Noble - Neyba
San Pedro - Hato Mayor