I wonder if there is any trick, for example if you roll to a traffic light to activate the idle, do not say to have any gear in it. Normally, the smart always switches down automatically and reduces the speed by the correspondingly inserted gear. Thus, although you only have to roll, you have to give gas, in order not to stop completely. In my opinion, this increases the fuel consumption and the wear of the clutch / gear. If I put the N gear in front of a red traffic light this would work in principle. But if only the traffic light unexpectedly jumps to green and I have to give gas, I do not know if it would be good to put the “gang” back in, because the car does not know which gear it should take and possibly switches into the first gear and then I would slow down quite badly. Does one of you also know this “problem”? Smart 451 cdi 2009