There are two very different ways to use a premium fragrance in a detailing business, and the difference between them is bigger than it first appears.
The first is treating it as a one-time add-on: an optional upsell offered at checkout, used inconsistently depending on the job, the client, or whether you happened to have stock that day. This works fine as incremental revenue, but it never really becomes part of how clients think about your shop specifically.
The second is treating it as a signature standard: the same fragrance, every time, on every top-tier job, whether the client requested it or not, built into the price of your premium service rather than offered as an option. This is a bigger commitment, and it pays off differently. Over time, that consistent scent becomes associated specifically with your shop, the same way a signature scent in a hotel lobby becomes part of that hotel's identity rather than just a pleasant smell.
The financial math works out similarly either way if you are pricing it right. The real difference is brand equity: an add-on generates a little extra margin per job. A signature standard generates recognition, referrals, and a repeatable experience clients specifically associate with you, which compounds in a way a line item upsell never does.
If you are still treating your fragrance choice as optional and inconsistent, it might be worth deciding, deliberately, which kind of asset you actually want it to become.