High pitched whistle when foot comes almost completely off the throttle, more in low gear. Seems to be coming from left front side. Any ideas?

 

High-flow induction system. IE Air intake. Completely normal for this car.

 

Could you please explain for the uneducated, what IE stands for. How come it seems to be audible only at certain times? Because the engine noise is not drowning it out? My wife told me it was because I bought a car with all the bells and whistles.

 

I e \I. e.\ Abbreviation of Latin id est, that is.

I'm hardly a technical expert but here's my best shot.

You will notice the air intake when in lower gears because:
a) You're more likely to experience higher revolutions (RPMs) in lower gears. (You can take the engine to 4,500 or 5,000 rpms in 1st or even 2nd gear on city streets without attracting a lot of attention. But in 3rd, 4th and 5th gears, the car is going really fast at those RPMs.) At these higher revs more air is being sucked into the engine.
b) The air intake is more audible when there aren't other noises to drown it out. These other noises could be wind noise or road noise coming through the tires. The sort of noises that you hear when the car is moving faster.
c) The engine is really just a big pump. It pumps air for the most part and when you lift your foot off the throttle the pump keeps running. The sounds the engine makes when you're off the throttle are somewhat different from those made when you're on the throttle. My guess is there might be a lull in the exhaust noise that allows the air intake noise to be more noticeable.

I could be completely wrong and your car might be malfunctioning. But I drew my conclusions from the fact that you said the noise came from the left front side and if you open your hood you'll notice the big tube (that's the air intake) running along that side of the engine compartment. I also hear the noise on my car and it's been written about extensively in car reviews etc.

Cale