Still other sensors (in smart cars) will track and record the wear on parts and systems, alerting the driver to potential trouble, and will even flash warning when pressure in the tires is too low.

There was no warning, only a leap in like a flash, a metallic clip of teeth, a leap out equally swift, and Curly's face was ripped open from eye to jaw.

Such devices may eventually be able to measure the level of cholesterol or alcohol in your blood and flash up an appropriate warning.