Hi, I was driving my rx450h quite happily along the motorway and when joining a slip road suddenly noticed a huge amount of white smoke coming from the rear of the car. It lasted approx 1 minute or so as slowed the car down worried what this could be ? Has anyone had a similar occurrence ? having looked through the Internet it could be anything from condensation ( although I had been driving for over an hour at that stage ) to head gasket to overheated brakes ? Not sure but worried none the less. Any help or advice welcome. Thanks