Hi all. No one at the dealer seems to know, I could not find any reference to it in the manual. You can clearly see the difference in the attached pics. At first I thought the light was replaced with one from an older model, but several of them are like this at the dealer.

 

My guess is the rear fog light is in the right rear taillight so normally the lights will be the same size when on. If you activate the rear fog light it will light the extra red ring to add to rear viability in crap conditions