Long long ago when I was in the motor trade, we used to charge £150.00 for something called Diamond Shine. It was a spray on glaze type treatment that cost the dealership £70.00 for 25 litres and was applied in two minutes by some poorly paid valeter. It was 'guaranteed' for two years. Nobody ever came back to complain. If they had we would have just sprayed it again. Total waste of money, that made no difference whatsoever. A good detail or looking after it carefully yourself would yield far better results. However, I am sure BMW wouldnt mislead customers in the same way to get you to part with £300.00 :roll: