I hear a whining, mechanical sound from the rear of the vehicle But only after long periods of rest.

Any body know what that is? I don't have NAVI, Multi-Disc Player...so I'm a bit puzzled. I'm sure its completely normal, but I'm just curious is to what my car is doing

 

Might need to qualify this with some parameters.
Is the power off when you hear it. Like, been off for more than 15 minutes?
Do you have convience package?

When I put the fob in the slot I hear the fuel pump pressurize the fuel line. Last a second or two, then shuts off.

 

Okay...yesterday...I get home, park the car in the garage...It sat for say 1.5-2 hours...then my buddy comes over and I show him my car. I open the passenger door, Ihear the familiar window thing, and I a hear a mechanical whiring noise near the rear It's done this before in the past after long periods of rest, but thought it was normal. But being the curious guy I am, I have to know

I have the premium package, and that's it. Hope that helps.

 

I believe it is the gas tank purging system.

 

Okay...general area makes sense...so I'll buy that. Is that the vapors from the tank being purged? This is also different from the hissing sound I hear from the front section of the car? Which I assume is purging the exhaust from the turbo.

 

I believe it is preparing the fuel system for starting. It does that when you open the door so that firing the engine will be a quicker process.

 

It is the fuel pump pressurizing the fuel lines.

 

Agreed.... It is your fuel pump charging the system. It gets pressure in your lines all the way up to the injectors so that the car starts quickly and does not have to turn over several times before the fuel get into the cylinder.

 

Thanks...that makes sense.

 

hissing sound from should not be the exhaust purging from the turbo since the exhaust is open from the turbine on. it is more likely to be the water pump cycling coolant to cool the turbo after engine shutdown.