Anyone who thinks talk is cheap should look at US transportation secretary Ray LaHood's testimony on Wednesday. Between the time he suggested Toyota owners stop driving their cars and then sheepishly retracted his comments, he had reduced the carmaker's market value by nearly $4bn.

Still, the damage was done and Toyota has compounded it by misunderstanding US consumer psychology. Safety scares often take on a life of their own, much like their spontaneously accelerating cars are allegedly doing. Only decisive action from the top of the company can reverse its momentum.

There need not be proportionality between the seriousness of a defect and its commercial consequences or even actual claims, as Audi discovered to its dismay in the mid-1980s. Unexplained sudden acceleration led to an 80 per cent sales drop that nearly pushed the marque out of the US. A television exposé, later revealed to be doctored, fanned the panic in that pre-internet era. Audi victims' woes might be dubbed as Vorsprung durch stupidity as a later inquest exonerated the company, concluding that drivers unused to European luxury cars had mistakenly stepped on gas pedals.