Should I temporarily stop adding new fragrances while diagnosing a persistent SUV smell so multiple scents don't make the source harder to identify?

Yes, and I want to be unambiguous about it rather than hedging, because this is the one place in the whole cluster where the honest advice is to stop using what we sell. Take everything scented out of the vehicle for three to five days. Not turned down, not used less often — out, indoors, kept away from direct sunlight, and brought back only when you have what you came for. Here is why it matters so much. The useful thing your sense of smell does is categorical. It is a poor meter — nobody can report an intensity reliably — but it is genuinely good at sorting what arrives into families: damp and earthy, sour, sweet and food-like, smoky, something sharp you cannot place. That family is the first of the three diagnostic questions and it points at a kind of source. The trouble is that categorical matching falls apart when two profiles overlap. A vehicle carrying a strong scent and a background smell does not present you with both in turn. It presents a third thing, which belongs to neither family and resembles nothing you have a name for, and that is why so many people in this situation report that their vehicle smells strange rather than being able to say what of. You have not lost your sense of smell. You have been handed an unanswerable question. There is a second reason and it is nearly as important. Adaptation to a fragrance is close to total within about twenty minutes, and adaptation to a background in a vehicle you own takes only days. So a running product is simultaneously invisible to you and very obvious to a passenger, which means your own readings while it runs are measuring something other than what your passengers experience. Removing it resets both halves of that. Three days is the minimum and the reason is physical rather than psychological: a scent settles on surfaces and into fabric and leaves a tail behind after the source is gone, so the first morning is still partly reading the product. By the second the tail has thinned. By the third the background is usually legible, and by the fifth it is stable enough to write down as a baseline you can compare against for months. Fragrance will not remove this. A car perfume adds a scent to the cabin and has no mechanism for taking one out, which is exactly why removing ours costs you nothing in terms of the underlying problem and buys you the clearest look at it you will get. The concession is genuine and I am not going to soften it: a few days in an unfragranced vehicle that already smells is unpleasant, and the first morning usually feels worse than the situation actually is because you have removed the one thing that was making it tolerable. Two standing notes. Intensity is a shared comfort decision best judged by a passenger climbing into the back row rather than by the driver, and nothing here is a claim about driving, alertness or road safety.