rjk

So of course the dealership isn't going to diagnose this since "the car's not supposed to be driven that way" - but I get a nasty rumbling noise when I accelerate from a dead stop with wide open throttle. It only lasts for the first few thousand RPMs in first gear, and after that it is gone.

I was guessing that it might be the transfer case or something like that, but it's really hard to tell. I do have AWD. Has anyone had this? I did not have any such problem in my previous GS, which was a 2007 (current is a 2010). It's worse when I accelerate around a corner, and it also makes a small noise when I'm going above 80ish mph, which of course the dealership isn't going to diagnose either.

lex-ative

Any lights? Any chance it being the traction control kicking in?

rjk

No lights. I don't hear any wheel spin, so I don't think it's traction control - it's also not a sound I heard on my previous car with the same tires, so I don't think I have a reduced amount of grip (Michelin Pilot Sport A/S tires).

If I actually break traction, I have seen the skidding car light come on with a beeping sound, but I don't get that light when I hear the rumble from a hard takeoff.

EA6BMECH

I had a Mazda Van that did it. I think it was to torque converter. 2nd gear wouldn't do it, just first from a dead stop. Now on the Dodge/Chrysler vans, they had to have MOPAR tranny fluid because of its viscosity? Mmmm something to that affect because foaming and the small orifices in the tranny would cause it to "rumble". Ahhh, I think I'm close on that one. Anyhoo. Good luck on that one