Like some of the others, I don't sew in the car, as I am usually the driver.
And when I do have the luxury of a "chauffeur", I like to enjoy the view!
Though I do have a travelling sewing kit for waiting room sitting or while in hotel rooms, etc.
Part of that is a sewing lanyard, complete with a mini pin cushion, and a magnet as a needle nanny.
Attached are also a small pair of scissors on a string, so they can't take off. Or get left behind!
Thread can also be added to the collection, if you so desire.
This way, I know I have everything at hand, especially when there is no sidetable to set things.
For hexies on the go, a CD case with the fabrics and hexie papers/card in each of the divider slots.