I wish I had a good answer for you. When I call folks for interviews, I often recommend that they wear no perfume or cologne to interviews, because it almost immediately prejudices the panel (and never in a good way). But in your case it is much harder, as you are asking for change after the fact.
I agree, perfumes in MANY settings is inappropriate. For me it is restaurants -- how am I to enjoy my food if all I can taste is the perfume of the lady 3 tables down. Or hiking...I remember once on a long hike, when we stopped to rest, and we could tell someone was coming up long before they arrived. That time it was the guy's cologne.
The best I can think of would be to catch her at the end of the day, or call her over the weekend, and just try to present the issue in a positive manner. Something like: "I like your perfume, but first thing in the morning in the car it is...overwhelming...could you do without, use less, dilute it, or put it on after getting to work?" I wish I could think of something better.
Anyway, good luck. I hope someone presents a better idea.