I'm also in Southern California, and I think that the hot/cold transitions have much to do with it, in addition to whatever bouncing on the road the car does. Living here, I've had generally good luck, although I have had some rattles in every car I've owned--Mazda, BMW, Toyota, doesn't matter. All cars (at least those that most people can afford) have plastic, and plastic rattles--temperature, etc. have an effect. Some are really bad enough that you have to try to get them fixed. Others are tolerable and probably can't be diagnosed anyway, particularly if they're intermittent. I've also had rattles that simply evaporated after a few thousand miles and never appeared again, perhaps because the frequency of the vibrations changed to where they could no longer be heard.

I've had good luck with my RX-8 for its first thousand miles or so. Just a very slight creaking sound near my driver's side air vent. Although some of the parts of the interior may not be the strongest, judging from other posts here, the overall fit and finish of the interior nevertheless seems to be very good, and pieces slide into and out of place correctly. That's a plus, and makes me a little more hopeful.

 

Yea, rattles in modern cars **** the hell outta me.. So far I've been lucky with my 8 (knock on wood) Some days I get a rattle from what sounds like the rear speaker area, some days its not there..

Very irritating.

 

The DC potholes/poor roads have beaten the hell out of my 8. I've got rattles in surround sound. My worst two are:

1) The stupid homelink rearview mirror - high frequency and irritating
2) One of the rear door's glass - sounds like glass hitting metal and it doesn't stop

 

Hey Guys,
I had the same problem had the mazda tech look at it. Right when he took it for a spin around the block with me in it he goes most likely its the foam inserts in the door. He went on to tell me how the factory dosnt have enough time to allow the glue to cure and this does happen. So they are gonna pull off my panels and glue them using a stronger bonding agent. I dunno but maybe you guys could get your techs too look at the door foam inserts. I was thinkin about getting them removed and just dynomatting, any suggestions?