Strange gearbox,steep hill
 

Hi, not sure if this is the same for all 370z but on a steep downhill if I'm behind another car so not using the throttle, going down the hill on the brake the gearbox drops down gears and iver revs, even using the paddle change it keeps dropping gears and over revs it's something I've never experienced in any other car, any ideas, thanks

Generally, that's just smarter programming, engine braking to reduce brake wear and preventing accidental run-away on long and steep downhill. It's not new. Some do it smoother, earlier, and less noticeable than others. My G does the same.

Where I came from, in the old days, people were taught to do this manually during driving school (auto or manual cars). Nowadays, computers do that.

How high rev are we talking about here? And, how long after you manually upshifted before the tranny decided to downshift again?

I understand what you mean but the gearbox is going back to many gears and reving between 5-6k on the tachometer, same thing using the paddle shifters, if I manually put it it into 6th and continue braking down a steep hill it down shifts itself another gear and over revs, it's something none of my other automatic car's has ether done, it's braking the car but going back to many gears,

Ok that isn’t normal…