I just want to share my horrible experience with this vanos issue. I am third owner of '08 E92 M3 with 57k miles (purchased it with 47k). I noticed in BMW repair history that around 13.6k it has a vanos issue on bank 1 and was replaced.
Now at 57k I was driving normally on the freeway and I get message of power reduction, red line dropped to 4k, lucky I was not far from my bmw dealership. Took it in and diagnosed the car and told me bank 2 is having vanos issue. Great! I said, long story short I was out of warranty at 55k (extended 5k because it was a demo car) BMW goodwill this repair as I pointed out how this should not happen and the fact that bank 1 had an issue.
So the repair took couple of days as parts needed to be shipped, I go pick up my car and start it up, sounds great I am happy camper! Then before I put it in 1st gear I see service engine light on, I turn my car off and let them know, they go back and diagnose it and then tell me the other vanos gear on bank 2 is off and most likey needs to be replaced. This time bmw will not goodwill and offer me "bmw warranty pricing" of $1300. This is where I am at now and my car should be done by tomorrow.
Also I was doing some research and people say that when you cold start you hear this rattling sound after you start your car *thread here*
I had that noise with my car when I cold start from 12+ hours of sitting, once I get this vanos replaced I will see if my makes any more rattling sound and confirm if this is true because if it is then its a sign of things to come and it might not be good.