When starting the car there is a knocking noise just as the engine jumps into life not everytime maybe 50% of the time it also does it sometimes when you turn the engine of, if the door or window is open you dont hear the knocking at all, this makes me think it is exhaust touching a heat shield or something and with the window down engine noise drowns it out, the car does not knock when revving hard in any gear including 1st or backing off, I would not want to take it to renault only to be told its not covered by the waranty (exhaust alignment) and come out with more than just a knocking noise if it is the exhaust I would take it someone I can trust and pay them to sort it