Brief answer:

• Ahimsa (non-violence) is the guiding principle. Jains try to minimize harm to living beings in all activities, including travel.
• Using a car is not forbidden, but it should be undertaken only when necessary (for safety, health, or essential duties, such as pilgrimage or family needs) and with effort to reduce harm as much as possible.
• People who take a stricter view may prefer walking, cycling, or using non-violent transport when feasible, especially to limit accidental killings of insects or small creatures.
• In daily life, Jains may adopt careful practices to lessen harm while traveling, such as choosing routes and times that reduce harm and being mindful of living beings around them.

Nuances among Digambar and Shwetambar traditions:

• Both traditions emphasize ahimsa, but there can be differences in how strictly lay practitioners interpret and apply those restraints. In general, travel by car is considered permissible if it is the lesser-violence option and if one remains mindful of minimizing harm.

If you’d like, I can share a concise Jain teaching (arth) on ahimsa in daily activities or point you to a Jain Knowledge page that discusses ahimsa in practical life.