I've taken my ball pythons to my classes on several occasions (I'm a teacher). In fact, I just took my Sulfur Mojave yesterday. On all occasions they've tolerated handling very well, and on the few occasions that I've offered them rats in front of everyone, they ended up eating them... and this was after being held, screamed, and gawked at by 140 teenagers at the end of the day.
A public event like a car show however is completely different from a controlled classroom environment. All of my students know how much I love snakes and animals, and know the value of my ball pythons, and treat them with much respect. If you do plan on taking your snake with you, be selective on who touches/holds it, and bring some hand sanitizer... you can never be too cautious.
Mark