Here's a tip for persons with cars that have a non-functional Comfort Access. The CA on my 2007 335i coupe stopped working about a year ago. I put off having it repaired, because of the known cost of replacing the interior antenna, and stories of cars that have had this replaced, without correcting the problem. The other day I had to have the car battery replaced, and lo and behold the CA now works perfectly . It appears that reduced battery voltage reduces sensitivity of the CA antenna to a level that prevents it from functioning.