This high-pitched whistle noise is intermittent and won't rear its ugly head until 30mph. Will continue to whistle at all faster speeds. Have removed cross bars on luggage rack and that wasn't the solution. Heater on/off makes no difference. Seals on windows look good. The vehicle has 55K and is in excellent condition. It's been doing this for 5 months. Dealership couldn't replicate sound--of course!

Thanks for your thoughts on this.

 

On a trip to the dealership for another issue I mentioned the noise again. Upon picking it up they said they'd stuffed some insulation around the glove compartment. Sure enough that was it. I'm happy.