nobody knows what it is. Even if I go up to my locked car, and try to open the tailgate, it makes the noise.

mine makes the same noise everytime I unlock it. Sounds like air being released. Always thought it was lowering itself or something to make it easier to get in. Only thing is that would be pointless cuz u can't even see the difference if it does actually lower unlike the lowering on a range rover. So what is it?

my e70 makes the same noise and i think its kinda cool but it only makes it when i unlock it after 6 or 7 hours ..
i love walking up to the door and just opening it and hearing the noise LOL .. i dont think is the suspension because i dont see the car come down a little bit .. i dont know what it is

I've always thought that it was coming from the self leveling suspension. I'd be easy to confirm if the noise is only heard by 4.8i owners or 3.0 with the optional self leveling suspension. I have the 4.8i and I hear it in the morning

I have a 3.0si and hear the same noise all the time, no idea what it is

Maybe the car is taking a deep breath so it can get away faster :rofl:

It could be the fuel pump, that is building up pressure?

Do you see somebody's shadow on rear seats when driving???:rofl:

Do you have comfort seats, guys??? May be we are close:rofl: :rofl: :rofl:

I thought it was the self-leveling suspension, since my X5 kept making the same sound when the suspension was leveling ( I could see it) when I was jacking up the left rear of the car once to check something.

Yeap, I've observed the same thing today... The car lowers itself a bit while making that noise. It is hard to notice that while standing next to it, but you can get a better view from a distance when someone else opens it for you.