I got mine just three weeks ago and only have 900miles on it so far,
but I've notice some rattles from driver's side front door.
I've tried remove the door trim but afraid I'll break something....
Also should I go back to the dealer where I bought it? or a local mazda dealer will be fine?

 

any mazda dealer would be fine. but i would take it to the guys you bought it from. they'll take care of you a little better if they know you bought it from them. and yes, rattles are covered under warranty. give them any kind of info that will help them narrow down the culprit of the rattle. the more info they have, the more likely chance they can fix it.

i work at a dealership and it's impossible to find a rattle without all the details provided.

does the rattle happen when cold or hot? window up or down? door opening and closing? when music is on? you get the idea.

 

Its probably from your front door speaker.

Its not that hard to take the door panel down, its hold down by couple of those plastic Tabs.

oh for your question, like Dan said, any dealership is fine except that, u better be sure that u find a good one. Cuz most dealerships just gonna send you home with the "Cannot reproduce the issue", even u got ur car from them.

 

Any Mazda dealer will do the work for you.

Mazda has a 1 year adjustment period.
I went back right before mine was a year old and had them tighten a few screws on the visors and the center console. (I know I could have done it myself, but for some reason I felt the need to have them do it anyway) It was free, but you have to be without your car for the day.

 

Take it back to the dealer you bought it from. They should be able to take care of that for you free of charge.

 

the reality is that the rx-8 comes w/ complimentary rattles from mazda. yah- it sucks and we all HATE it. my car rattles too- ie the navi, the rear deck, the center console. i only have 7000 miles too. the fact is that unfortunately the 8 is not a Lexus, BMW, or mercedes.

my suggestion is, unless it's an obvious DEFECT, just live with the minor imperfections of this car, as it is not a high-class, luxury vehicle. if u go searching for perfection, not only will u be disappointed, but it's more likely the dealer will scratch, ding or do some other kind of nice complimentary damage if u bring it in to have them fix something like that.

just my 0.02...

 

The only thing that rattles in my 8 is the rear view mirror. and I am thinking of stuff it up with some kind of Rubber or something inside.