Best way to get from Zihua to San Miguel de Allende

We took the bus to San MIquel last year. There was no direct bus and we had to change buses in Morelia but only
had a layover of a couple hours. We actually enjoyed that, had a chance to get off the bus, stretch our legs and have lunch at one of the restaurants in the bus station in Morelia. The scenery along the way was fabulous and if you have never been on the buses in Mexico they are very comfortable and a great way to see some of the country while someone else is doing the driving. We stayed at a beautiful B and B in San Miquel and had a great time there!