We just returned from Chiapas to Lake Chapala through Oaxaca after driving down there last month via Veracruz State with detours to Cuetzalán and Hueyapan, Puebla and can report on our experience making the drive between Lake Chapala and San Cristóbal de Las Casas via Oaxaca versus via Veracruz State. While the drive through Oaxaca is still about 100 kilometers longer than the drive through Veracruz (without the lengthy detours we took this time), the drive through Oaxaca is a nice alternative to the drive through Veracruz and the timing will be close to the same once they have opened the Oaxaca City-Tehuantepec, Oaxaca Autopista - however, it ain´t open yet and the twisting mountain road between Tehuantepec and Oaxaca City makes this option more difficult for now. I don´t know when the Oaxaca City-Tehuantepec Autopista will open but they have been working on it for some time and it may be open soon.
The Arco Norte cuts about two hours off of the driving time from Jalisco or Michoacan and that makes a big difference. To figure the driving time from, say, Morelia to San Cristóbal, take about four hours off of the trip from Ajijic to San Cristóbal. At the speed we drive, which is at about 130 KPH, it now takes about seven hours to drive from Ajijic to Puebla City versus nine hours when we had to drive through Mexico City when the traffic flow was good. It is about 4 1/2 hours from Puebla City to Oaxaca City so the drive from Morelia to Oaxaca City should take a total of less than eight hours which makes the journey to Oaxaca an easy one day trip from Morelia and pretty easy from Lake Chapala as well.
When the new Tehuantepec-Oaxaca City opens to expedite travel from San Cristóbal to either Morelia or the Chapala Municipality, I estimate that the total driving time between San Cristóbal and Chapala will be about 16 1/2 hours via Veracruz State and about 17 1/2 hours via Oaxaca City. That should make the drive between Morelia and San Cristóbal about 12 1/2 hours via Veracruz State and about 13 1/2 hours via Oaxaca City if one travels at the speed we drive. This is an amazing improvement which should open up Southern Mexico big time once that last leg through Oaxaca State is open.
I´ll post more about this road trip plus some very good and very mediocre places to eat along the way when I have more time.