Bath and Body Works Refills car fragrance lasts approximately 4-6 weeks. However, some factors can affect the duration of the fragrance. High altitudes and extreme temperature changes are the main factors that affect the life cycle of car fragrances. When using liquid air fresheners, most car fragrances still have liquid in the fragrance capsule even after the fragrance has faded, making it difficult to know when it's time to replace it. I'd say it's safe to replace it every four weeks to keep your car smelling fresh.