The car dealer can be held liable for any faults that develop within the first six months. This is because the fault is considered to be present or developing at the time of sale. After this time frame you'll need to prove the car was faulty at the time of sale. A report from the BMW garage might help with this. But the line of liability is generally with the independent dealer that sold you the car and not BMW UK. For your legal rights, see: www.honestjohn.co.uk/how-to-reject-a-car-your-cons...s