Hoping Gilly can give me tips on this :-)

I have a whistle (sounds like a light teakettle whistle) at 60mph or higher. Dealer hasn't been able to reproduce it, but it's a bit annoying on long drives. If it whooshed, it'd be much less annoying :-P

Any suggestions on how to locate it so I can point it out to the dealer? One of the seals is obviously not sealing that well, but I have no idea if it's a door seal or window seal or where it might be. Only thing I can think of is to close the door and ask someone to sprinkle talcum powder around the door and window seals and take it up to speed and see where it leaks in, but I haven't tried it yet because it'll be pretty messy....

thanks,

ken