Noticed my 3rd tail light was completely non functional the other day when my wife took the car. Seems this is not an entirely uncommon event in the 500c as I found several other references to it in forums. Be aware there is no indication the light is not working, no dash warning etc. From what I have read the wiring in the top is getting crimped or otherwise damaged when the top goes up and down. Took a look, mine has a really tight 180º crimp that may be the culprit. Off to the dealer next week for a looksie.