I park my MY05 G35 sedan on an inclined driveway. Whenever I disengage the parking brake and pull back in reverse (and onto more level ground), I hear a distinctive "boing," like the sound that a bouncing spring makes in cartoons. The car does not make the sound at any other time. Any idea what it could be?

Thanks!

 

I'm not too sure it happening when in reverse but when you first start the car and move forward, the ABS self checking system goes on which sounds something like what you are describing. Only happens when you start the car and start moving and hit about 5 mph. Here a thread I posted about the same topic and there are some links on that thread as well with other drivers experiencing the same thing:

https://g35driver.com/forums/g35-sedan-v35-2003-06/51274-boing-sound.html

 

thanks Kei, that's it exactly. Serves me right for not reading the owner's manual carefully enough.

 

no problem!