Very irritating noise that is audible almost always above 80 kmh (50 mph). It sounds like a harsh cat's purr but more metalic and perhaps a bit faster.

The vibration speed does not vary with road speed or with gear speeds but appears with relation to wind speed: Almost always once I get above 100 kmh (60mph) and at lower speeds when there's a head wind. Normally, it appears by about 80 kmh (50mph).

It is harder to hear on wet roads (but I can still hear it because I've become so sensitized to it) and when I have my snow tires on.

Two different Mazda dealerships have had two or three attempts at discovering the cause but can find none. I have also contacted Mazda Canada but only got a PR guy who said he'd check it out and get back to me but of course he never got back to me.

I've suggested the service department at my local dealership in Abbotsford, BC, take my car for a week or so in order for them to really get accustomed to hearing the sound (they claim they can't hear it when I've taken a mechanic out with me and they obviously are not listening to what I'm saying as they later report I tell them of a "knocking' or "creaking" sound whereas I've always described it as a "vibration" noise). Listening to my cat one day I realized its purr was the best comparison and I've been using that analogy ever since.