I have a 2020 CX5 Signature (turbo). For the past year or so, I've had a very annoying rattle that only happens when accelerating. It stops the moment I take my foot off of the gas. I hear it more often than not, but appears to be more of a cold weather issue. The noise was not present over the summer.

The sound appears to come from the driver side area, perhaps below the dashboard, but it is very difficult to isolate. I tried to press on every panel to try to see if it silences the noise without any luck.

This video was taken on my way home from the dealership, after they were unable to replicate the problem. After sharing this video and leaving my car there for nearly two weeks , they told me that the sound is normal and 100% what they would expect a turbo to sound like.

I’m interested in hearing what others think. Does this sound normal? Any ideas on what the sound may be?

 

Myself, I cannot hear any rattle in that video. It's either faint enough or not obvious enough. (I've got a couple of little "buzzing" sounds in my own 2016 CX5 GT, mostly when colder, up in the A-pillar, something that doesn't always occur.)

In the pillars and within the dash area are any number of little spots where a rattling or buzzing could occur. Something not tied down properly. A cable tie or mount that has come loose. A section of batting or insulation that no longer is properly in place, or has worn, allowing the protected/anchored stuff next to that batting to now come into contact with a hard surface. Cold makes certain materials a bit harder, less-moldable against other nearby parts, enhancing the likelihood it'll rattle or buzz during cold weather but not so much during warmer weather. Could be any number of things in the area, plastics or wrapped wires or whatever, which exhibit greater likelihood of such noises in colder versus warmer weather.

There are a few things that can be reached up under the dashboard, but many require removal of the dash. (Same with the pillars and headliner, with rattles and buzzing in those places.) If you can readily duplicate such noises while in park but while using the throttle, perhaps get another person who can also hear the rattle to press various parts of the A-pillar and dash area, grab and move various cable bundles and parts that can be reached from the pedal area underneath the dash. Perhaps you can get lucky by immediately eliminating the rattle. At which point, it'd be highly likely the part yanked (or one nearby it) could do with better anchoring, protection with batting, etc.

Not much help, I know. But these little noises can be pernicious and hard-to-find buggers.

 

My virus protection software will not let me download your video.
Check out this thread, it may have some info for you.
Rattle at 35-45 mph - Mazda Forum - Mazda Enthusiast Forums

 

https://m.youtube.com/watch?v=Bjxdypc3LVc

 

Lol honestly I know you are trying but I get these kinds of video's send to my emails, and PMs every week. They dont help in this case. So, I really recommend doing what some of us suggested in this thread and return to a dealership that will go with a ride-a-long so you can tell the service representative exactly when it is happens and what you are hearing!