when I'm braking before stopping completely the car rev is this normal.G37s?

 

I believe that is the downshifting

 

For some years there were TSB's / factory updates to the software so the shifts were made milder or omitted. Early versions were very "sporty" :-) You might check and see if your software has been updated if you don't like the downshifts when you brake.

 

Yes take the car to the dealer and have them update your trans software

 

Is there a cost to updating software (ecu, trans, etc) and would there be a cost to check if my software is up to date?

 

If your car is out of warranty, dealer usually charges $150 to hook up the Consult to check. I think TSB updates might be included in that price but I'm not sure.

 

I think the OP is talking about the rev-match feature when the car downshifts in DS mode....which is normal. If your engine is revving on downshifts in regular D mode then that's probably an issue