I was driving behind my wife today, she was driving the GLS and for the first time I noticed the tail lights when applied are different then the GL. When the brakes are applied its just the top outside square that illuminates. I knew the design was a bit different but did not know the function changed too.

 

Does anyone have pics of this, meaning with the brakes applied showing the difference?

 

I found pictures. The 2016/17 are the same but the 15's and below differ. Here is a picture of a 17 and 15 with brakes applied.

 

Also I might add the European/Canadian models may differ.

 

Brake lights are not applied on GLS in this snap! LED strip brake lights on the top are off..

 

My brake lights on my GLS450 when applied look just like the pic above on the GLS550.

 

No, the brakes are not applied on the GLS550 in the above picture. The car has hazard lights on. Those are signal lights, not brake lights.

 

After looking at that pic again, you're right, brakes are not applied.

Here is a better pic with brakes applied.

 

Yeah, I see brake lights as well as hazard/signal lights on.