Hi all.
New to the forum so hope I'm posting in the right place.
I own a 2010 (series 2) SX4 AWD MT hatch. Great little car, but noise from drivers side door area above 80kph had been driving me mad for last couple of years. Is like a buzzing, rattling noise. Decided to get to the bottom of it recently so started off by removing inner door card and checking for any loose screws or trim pieces. There was nothing obvious but stuck some extra rubber adhesive around the place, including where plastic dust sheet goes over apertures in door (thought it might be reverberating at higher speeds). No joy. Then had brainstorm and started tapping around front quarter panel. Sure enough, there was the noise. Turns out there is a plastic baffle that fills the gap in front of door hinges, which was rattling at higher speeds. Solution - a can of expanding foam sprayed in the cavity. Had to remove mudflap and inner wheel trim to get nozzle of foam dispensing can in there. Best method is to hold (or temporarily screw) inner wheel trim back in place then poke nozzle into the holes where the clips were and spray away until the foam starts coming out. Remember that it keeps expanding so don't get too carried away. Unfortunately didn't think to take photos at the time but have included a photo I took afterwards that shows the plastic baffle (can just see the white foam). Bear in mind this is RHD vehicle (from Oz). Hope this might help someone else that's frustrated with trying to track down elusive noise

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