Scenery is the main attraction in County Cork, and unless you're a biker or hiker, the best option for taking it in is to rent a car, although regional buses do run on main roads. Once behind the wheel, plan to adopt the local pace—slow. Covering about 100 km (60 miles) a day is ideal, with many stops along the way. Speed is dictated to some degree by the roads: most are small, with one lane in each direction and plenty of bends and hills.
The main driving route from Dublin is the M7 motorway, connecting with the M8 in Portlaoise to continue 257 km (160 miles) on to Cork City. The journey from Dublin to Cork takes less than three hours. A car is the ideal way to explore this region's scenic routes and attractive but remote towns. Except for Cork City, where you're best off using a garage, parking is relatively easy to figure out.
County Cork has good, wide main roads (National Primary Routes) and better-than-average local roads (National Secondary Routes), both known as "N" routes. Regional ("R") routes can be narrow. They're also used by hikers and cyclists from Easter to October, as well as local traffic, which can take the form of school buses and huge trucks serving the local agricultural co-ops. The speed limit on these Regional routes is 80 km per hour (50 mph), but use your common sense and adjust your speed accordingly. If traffic builds up behind you, it is customary to signal to the left, and slow down (or pull off the road if there is space) to let the locals whiz past.