Active Curve
 

How can I determine if Active Curve is active/installed?

I ask the dealership for the datacard using EPC. It'll list if it has Active Curve or not with the VIN.

I'm not sure if there is a way to turn it on and off? I have it, but never bothered to check how to use it, i figured it was always on?

anyone else have thoughts?

If you see a "Sport Mode vs Comfort Mode" button in the center console near the round knob, you have it. If you have an AMG, I believe it comes with it.

You can also look up your options based on your VIN:
carinfo.kiev.ua/cars/vin/mercedes/

My GL350 has it and it's a MUST (for me).

Option code: 468 ACTIVE CURVE SYSTEM

Go to this website and put your VIN number in there
http://www.vindecoderz.com/EN/Mercedes-Benz

If you see the code 468 in there, that means you have it.

when you select sports/comfort model, the display will show different words, for gl without active curve it will just say something like switching to sport/comfort model, but with active curve it will say switching to sport/comfort model with active curve.

Anyone know how to determine ACS is active/installed on a GLS450?

Mine says:
468 ACTIVE DRIVING STABILITY (ARS)

Type in your VIN # into http://carinfo.kiev.ua/cars/vin/mercedes/

Thanks for sharing.

With EPC not free anymore, I was wondering how to get the data cards for free.

I recently purchase a 6-DVD set service manual that covers all MB models 1986-2014. I could look up things for you.