Depending on where you live and when your trip is planned for you could look at doing a course with Galmatic. http://www.galmatic.com/
They are based in Syd but do run some courses out of Brisbane as well. Defensive driving and get to know your car workshops for Women.
Sorry edited to finish what I was typing... You could try and make it a group thing so you're not pointing fingers at her in particular...I probably still wouldn't get in the car with her though. If it was me and my friend I would do everything I could to encourage her to calm down on the roads. She sounds like an accident waiting to happen and I would hate that accident to include one of my family members. Scary stuff.
Enjoy your trip in any case, it sounds like fun.
This post has been edited by shelly05: 08/11/2012, 03:31 PM