Like every two lane non-toll road in Mexico that one is not a high speed highway. I've driven it many times and it does not have hairpin curves or wild grades. People who are unable to maintain a 60 mph average on Mexican roads complain but I find this route to be not challenging. Depart Oaxaca City at the crack of daylight and you will have plenty of hours left once you reach the coast. Anytime you can see two or more houses alongside the road watch for speed bumps anywhere in Mexico. I've driven my 40' 3-axle bus up and down that road. Going up is more of an experience because of the possibility of encountering an overloaded six cylinder dump truck struggling on 4 cylinders. You'll do fine.
