Give it a try, but I'm 99.9% sure that won't work. The CAS comes pre-programmed with 10 key codes which are tracked by the dealer, two of those slots are filled at the factory if I recall correctly. One more limitation is that if your E70 has comfort access, only two comfort access keys can be assigned at one time (would require ISTA to deactive the lost or dead CA key before the new one is activated).

The way the gray market keys works is by violating this part of the document you cited "The key number is part of the key detection. As a maximum of 10 keys can exist for one vehicle, the key numbers 1 to 10 are stored in the CAS. The key number cannot be changed." It turns out that aftermarket tools *can* change the key number. They read the key blank and modify the key number in the CAS. On vehicles that have had the CAS firmware upgraded to 3+ (encrypted CAS), a downgrade is required for this process to work. One more note is that on the E70, the CAS also authenticates the transmission - which has not been cracked in the case of the LCI - so if a "craigslist special" coder bricks your CAS you'll be in a bad way. Sorry if this isn't completely accurate as this is from memory.

This is me coding a new gray market key on my E90. It's the same process on the E70.



You can cut the physical key with a $100 security key cutter from ebay. I can make a video of that process if you'd like.