I'll be testing the warranty process this Friday when my car goes in for a lambda sensor change (well that's what I suspect it is).
I bought the car through the AUC specifically so it would come with a warranty, and I'll be renewing with BMW when the time comes for the same reason. These days I value my time far more highly so don't want to be trying to save a few £££ on the floor of a cold garage fixing things. I've had enough things go wrong on my previous BMWs to know that it may not pay off in full but taking the hassle factor into account it'll be worth it.