I've got a fun one for you that stumped my local shop. I've got a 2007 S with around 80k on the clock. In the last few weeks, I've noticed that when I'm driving between 60 and 75mph, there is a consistent, yet quiet (I can drown it out with the radio at low volume), squeak/squeal noise coming from the engine compartment. Any faster or slower, and the noise disappears. Based on the tests I've done, it's purely speed related. There is no correlation with changing gear (I've shifted from 4-6 at that speed with no change in the noise), or whether I'm approaching that speed range from the bottom or the top. It also happens regardless of how I have the climate control set, from all the way off, to full blast, AC/No AC, etc.

Any ideas? The shop poked around the engine bay and found nothing, they also tested for play throughout the front suspension and that's all still tight as it should be. Right now our game plan is to wait for it to get worse, which really isn't my favorite approach to repair .

 

How can you hear anything going 60 to 75 mph? These cars are so noisy I wouldn't be able to make out any strange noise at that speed. My car used to squeal at idle, ended up being a bad serpentine belt.

 

I have really sensitive hearing. When I first moved from the farmlands of Illinois to Chicago, I couldn't sleep for several days because I would wake up every time I heard someone walking past our front door. My girlfriend thought I was making it up, until she noticed that I could hear when food we were cooking was about to bubble over, in the oven, from two rooms away, while watching a movie.

My first thought was a belt of some kind, but I ended up discounting that idea because the noise is not correlated in any way with engine RPM. Maybe the belt has stretched some, and at those speeds catches the air just right and starts vibrating?