Picture the scene: a slippery road, dense fog, zero visibility. You hit the brakes and hope for the best, praying that the car behind won't slam into the back of you.

This scenario should become a thing of the past when all vehicles are fitted with car-to-car communication. These systems send information on speed, position and direction of travel via secure WiFi. The driver's actions - such as strong braking or activation of the hazard warning lights - are also transmitted.

A car networked in this way has a WiFi router with a range of around 500 metres, which can send and receive data even at high speeds.

"A range of up to 100 metres is sufficient for most urban applications," explains Professor Horst Wieker from the Saarland University of Applied Sciences.

The cars don't just "talk" to each other. Traffic lights can tell vehicles in real time the speed they need to go to cruise through the next green light. This saves fuel and reduces accidents. The system could also warn drivers of pedestrians and cyclists, or give them early warning that emergency vehicles are entering an intersection.

"The more vehicles are equipped with standardised car-to-car or car-to-x communication, the better they can warn each other," says Andre Seeck from Germany's Federal Highway Research Institute (BASt).

"A market penetration of 10% to 15% is sufficient for positive effects in road traffic," says Seeck. "This could be achieved in three to four years." However, it's estimated that it will be 17 years before the system spreads across the full market, even with the optimistic assumption that all new vehicles will be equipped with the technology from now on.

Volkswagen is selling the new Golf with car-to-x communication as standard for the first time this year. "The advantage is the direct real-time communication within a few milliseconds," says VW developer Thomas Biehle, "and it does not cost the driver anything because it doesn't use the telephone network."

Sadly, there is still no agreement on which standard is the best.

Mercedes relies on networked communication that can pass on information from the vehicle to other Mercedes vehicles via a secure cloud. "With this data, we are creating an advanced sensor that can look many kilometres ahead," says developer Nikolaus Kleiner.

BMW is taking a similar approach. In simple terms, their system transmits data over long distances via servers. "In this way, we can warn not only one driver over a few hundred metres, but everyone over a range of many kilometres," says BMW's Joachim Goethel.

Unlike Volkswagen, BMW relies on C-V2X mobile communications technology, an LTE specification adopted in 2017. Other manufacturers are also already developing systems with this standard.

BMW is striving for a platform through which all manufacturers and road users can exchange safety-relevant information.

Together with Daimler, Ford, Volvo and the geodata service providers HERE Technologies and TomTom, they recently launched a neutral server for the exchange and combination of traffic data.

 - dpa