Not sure how far from Dallas you want to travel but I think this would be an excellent drive, not sure why Boxstoberfest is not scheduled around this time of year.
Look at the following two links. The first is mainly about a State Natural Area but has some good info about what you will see. The second link provides a route.
Lost Maples | Chron.com - Houston Chronicle
Take a scenic drive to see Hill Country scenery | Chron.com - Houston Chronicle
Good luck and congrats on the new car!!!!!!