We have all seen it, some of us have done it, and a few have crashed as a result: a pedestrian is so engrossed in telling their friend which pub they are going to, that they walk straight out in front of a car.

It happened to one of our writers on a motorbike a couple of years ago: the dopey pedestrian was only shaken, but the bike was wrecked as the rider took evasive action. Only the presence of witnesses persuaded the police that the biker was actually the real victim.

Anyway, GM is working on WiFi Direct which uses Bluetooth, but not through the mobile network, Instead, it communicates with other Bluetooth-enabled devices within 200 metres within one second, rather than the how-long-is-a-piece-of-string delay of mobile phone networks.

That means the system could alert drivers that a pedestrian is about to cross the road in front of them, or a cyclist is in their blind spot.

It sounds a great idea, but it will take a lot of refining to filter out pedestrians that just happen to be close to the kerb and have no intention of stepping into the road. If the system gives lots of "false positives", drivers will switch it off in less than the one second it requires to communicate.