They never take their eyes off the carriageway for a moment and they see everything that happens on the road or in the car. The talk is of dashboard cameras - dash cams for short. A dash cam mounted on the fascia can document your behind-the-wheel behaviour and that of the motorists around you.
In some cases the surveillance footage of these devices is genuinely spectacular - such as the pictures of a meteor shower captured in February by a motorist in Chelyabinsk, Russia. The full colour images in brilliant detail went on news sites round the world.
A growing number of cautious drivers are discovering the cameras as a way of documenting accidents and of even proving innocence or blame in the case of road accidents when insurance companies are reluctant to pay up. In western European countries interest has grown too, although there is no guarantee that a court will recognise video footage in a law case. The typical dash cam is mounted on the fascia using a suction cap and when switched on it simply records the activity in front on the car during a journey. A rear-facing version can also be installed to keep an eye on the interior.
The footage is sent wirelessly and logged onto a chip card, enabling it be read on a computer. The camera gets power from a rechargeable battery or a cable attached to the cigarette lighter socket. Expensive versions often come with a separate camera which records activity inside the car, tapes sound activity and uses a GPS receiver to locate the vehicle, matching recorded activity to exact geographical co-ordinates.
State-of-the-art devices react to by acceleration, swerving, hard braking and other potentially hazardous situations. Most dash cams automatically rewrite over uneventful video sequences, so that the owner does not have to laboriously delete old files. The technology has long since come of age, since cameras like these have been used to film car races from the cockpit for years.
Analysis of the videos helps competition drivers shave seconds off their lap times or correct driving errors. Off the track the reasons for installing a dash cam are naturally more prosaic. "Many drivers just want some hard evidence in case of an accident or if someone makes a claim against them," said legal expert Markus Schaepe who works for the huge ADAC motoring club. "It's worth noting however that the cameras also record footage of third persons too."
The legal status of dash cams has not been clarified in most countries and it is by no means certain that camera footage could help someone prove innocence in an accident situation. "A video can be used as evidence if the court is satisfied that there has been no manipulation," said Schaepe. Having dash cam footage might actually backfire if a driver has not been obeying highway rules.
In the case of a crash, if police have grounds for suspicion, they might confiscate the camera and use the footage against the owner. "The degree to which videos like these can be used is always within the discretion of the court responsible," said Cathrin von der Heide from another German motoring association, the Automobilclub von Deutschland (AvD).
The organisation warns members explicitly against relying on footage as legal evidence. Rainer Hillgaertner, press spokesman for the Auto Club Europa (ACE) went a step further: "The videos can lead to the court wanting to examine the accident circumstances more closely and that can be counterproductive." Electronic systems used to monitor driving are not new. Such "black boxes" - similar in design to those which record flight activity on board aircraft - have been fitted to heavy commercial vehicles since the mid-1990s.