How do I tell that my car has this sonar feature?

I've got a 2013 G37x with Premium package

 

I think the sonar system comes with the premium package so you should have it. The easiest way to tell is to either look for sonar emitters on the rear bumper (they look like little circles) or look for the button that turns them off (I think it's on the lower left of the dash near the trunk release and traction control buttons but I'm not 100% sure about that)

Alternately, just back up close to a wall and see if your car starts beeping. They usually start chirping around 2 feet, give or take.

 

If you have a 2013 G37x with Premium package then you have the rear sonar system.

 

Reverse toward an object, listen for beeps. Try not to crash into said object.

 

What did you think the circles on the bumper was?

 

I needed a laugh, thank you

 

Good to know.

so, does anything need to be done to turn it ON or is it ON by default when the car is placed in reverse?

 

this one

 

You can adjust the sensitivity of the sensors through settings on the dash. Factory setting the sensors don't pick up a curb. Backing in-between a car and the curb may not have the sensor go off. To test take a garbage can and put it behind the car and put the car in reverse it should go off. I though mine didn't work until someone was approaching the car as I was backing up and the sensor picked them up.