I have just over 100k on my smart. it is running like the day I got it except for start up in the 40-60 deg F days. On cold start up the secondary air injector whine is there but only after a squawky start up. when this happens it misses a bit and the check enjine light comes on with the misfire cylinder 2 code. sometimes it will go into limp mode. ( have to stop and restart then all is fine) not sure what to do to fix it. I think the Air Injector motor will smooth out. It could be stiff from the long warm summer.