I have a 2012 328i and I wanna retrofit a x5 style key to it. I have someone that can solder the chips to the key, I just don't know what key specifically I need and which ones are going to be compatible. I tried sending a PM but it won't let me. Here's some examples of the keys I think might work, let me know what you think.
https://www.ebay.com/itm/for-BMW-5-7...cAAOSwlMFdCI67
https://www.ebay.com/itm/Silver-Smar...IAAOSwhEtd1f2p