In my quest for a Z4, I went to test-drive few of them
. I fall into one equips with the comfort access and I was unable to open or close the boot remotely using the key :| . However, I have tested it on other Z4 with and without comfort access with no issues. The sale man assure me that it was due to a security bulletin from BMW :x . This feature is removed by a software update
... Have you heard anything about such security recommendation/update from BMW ?

