 I bought my Mazda 3 last summer after researching what used model would be best for the best price.  I was initially  impressed with the car for the price and mileage on the car.  The reviews were so strong on the resale and longevity that I was comfortable paying a higher price for a certified used car.  After a week the cabin noise was driving me nuts so I took it to my mechanic for a once over.  He told me that nothing appeared to stand out as the culprit for the noise.  I began looking on other websites to find a solution.  The consensus was that the light body weight that allows for speed also allows for road noise to invade the cabin.  For over a year I have just amped up the radio to cover the noise.  A week ago I received a notice from Mazda about a gap above the temperature and time display that separates during high temperatures.  They called it an "extended warranty program" and not a recall.   I took my Mazda back to the original Mazda service company.  During the repair, they did an inspection of the car and found the #3 motor mount had started to crack and leak.  These motor mounts are oil filled apparently.  Again, I researched before allowing them to fix it. What I found was that the Mazdas have a problem with their motor mounts and this is a common repair.  I thought great, maybe this is why the cabin is so loud.  When I picked up my vehicle from the service company, I could not start the car until the third attempt.  The front end shook like the engine was seizing.  But the car eventually turned over and was running.  The "repaired" dash also had a bigger gap above the time/temperature display. (add a lot of arguing, cursing, and freaking out here and then we will fast forward and save you the drama).  The service manager then told me that the Mazdas (particularly around my year) are known to have difficulty with "cold" starts after a "rich" start.  A "rich" start being the very first start, then if the car is not allowed to warm for ten minutes and is turned off and started again, it fails or delays to start.  He also informed me that the "gap" in the dash board is not actually what the repair was for, and since the dash does not have clips to pull the dash down to the clock, that this is what the repair will look like.  So this is the real truth, the Mazda 3 is known for it's loud cabins, cold start problems, bad motor mounts and gapped dashboard problems.  And all these things can't help you sell it and run like hell.