Hi, I'm new to the forum. I bought a used 2010 G37 sedan on March with 32k miles on it. Recently I noticed that when I brake hard or brake while going downhill my car jerks pretty badly and downshift. The RPM would hit 4.5k when it downshift. I'm not sure if that is part of the cars feature or something wrong with my car.

 

Downshifting going down hill is perfectly normal. I had a "wtf" moment when it first happened to me too. But the shift shouldn't be too harsh.

 

Were you in DS or D?

 

It's the rev-matching feature that you're not used to, but it's performing as it should. The harder you decelerate the more abrupt the shifts become.

 

Mine can be harsh going down hills also, no matter if I am in DS or D. It only happens though when I am romping on it before the hill, the car may be trying to be more sporty with its down shifts I think.