spung

Presumably the absence of one of these bits, which I see on the road somewhere at least once every day, is something a car driver would eventually notice and require to have treated. I'd have thought the very instant of their escape from the remainder, presumably fixed more firmly in place or retained in some way, would be a noticeable event, but then some people seem to not notice flat tyres, dragging exhausts or huge billows of black smoke emerging with every depression of the throttle-pedal.