So, I'm driving in the kids car today, 2012 IS250 AWD, and I notice that the engine noise in the passenger seat/side is much louder than the driver side! You can hear the engine/tranny rev up and down at almost twice the level it is on the driver side. Is this normal??? I've never experienced noise level differentials from the driver-to-passenger side like this in any of my other cars.

 

There shouldn't be any difference. Uhm, was the window down? LOL!

 

nope... it's not wind noise.. it's engine/tranny noise. coming from the floor well.

 

There's no way for us to know, need more info. How does it shift, at stop how's the idle? I've had this on another car but can't remember what the cause was. If it shifts fine when was the last tune up on the car? Is the engine light on? Throw any codes? Is it knocking? Too many variables without more info.
I'd take it to a mech(not the dealer unless you have money to dish out) and have them diagnose it. Don't have them fix it unless you're for certain you can't fix it yourself. Just my suggestion is all.

 

Shifts fine, though it seems to shift late, like stuck in 3rd/4th gear too long., but shifts are smooth.

The car has about 35k miles on it... no CEL , idles fine, new tires, car is under warranty, so not really worried about the Stealership and their crazy pricing... just wondering why the noise in the passenger side is louder than that of the driver side.