What are your tips for handling IBS urgency while driving or in traffic?

Handling urgency in public is difficult enough, especially if you can't easily find a public bathroom. But driving and sitting in traffic add an extra layer of stress.

If you commute to work or spend a lot of time in the car, do you have any tips for others who deal with urgency while driving? If you keep an IBS flare-up emergency "kit" in your car, what are some of your items?