Car freshies are not automatically stronger than other car air fresheners. They are one format among hanging cards, vent clips, gels, and sprays, and each releases scent differently. The fragrance formula and conditions inside the car matter as much as the format.
A spray gives a burst of fragrance when applied according to its directions, then fades. A hanging freshie releases fragrance over time, with warmth and airflow affecting how noticeable it is. A vent product interacts more directly with air moving through the vent; some models also offer an adjustment for output.
These differences can make one product seem stronger at a particular moment without making it stronger throughout its entire useful life. A freshie that smells bold when you enter a warm car may feel softer later in the drive.
If you like a strong first impression, read reviews for the particular fragrance rather than assuming every freshie will deliver it. If you prefer more control, look for a product specifically designed with adjustable output. Opening several fresheners together makes the result harder to predict.
Your vehicle matters, too. A fragrance that feels comfortable in a large cabin may be overwhelming in a small car. Try one product as directed before adding anything else.
Whatever format you choose, fragrance should complement a clean interior. Remove food, damp items, and other odor sources rather than expecting a stronger scent to solve the underlying problem.