I took the family on vacation to Texas a couple weeks ago. Flew into Houston, stayed there a few nights, then Austin for a few, then Dallas, for a couple then back to Houston for a few more and flew back.
Just mapping out the loop between the three cities is 9.5 hours and 623 miles. Add in slowdowns for poor visibility due to weather, stops to charge and use the restroom (with small kids), it was easily 12 hours, at least, of total road time.