I have ordered a 540iA--delivery in July, hopefully. The dealer has been trying to sell me on an application of a urethane film (called Autobahn) to the paint surfaces vulnerable to stone chips, bug damage, etc.--notably the front of the hood, front bumper and so on. Do any of the readers know anything about this product. Is it effective? Does it become discolored in time--and so on? Thanks for any input AB