They already tried this probably 20 years ago. The frequencies were allocated to car companies for inter-vehicle communication for exactly this purpose, and the car companies promptly did nothing with the technology except sit on it. Finally the FCC took it back because they clearly had no intention of doing anything with it. I can’t find a source, but I’m fairly sure it has now been allocated as the 6GHz WiFi band.

Qualcomm developed a tech for this:

https://www.qualcomm.com/products/automotive/c-v2x/overview

Mercedes has a concept (or maybe they have it on some models: https://group.mercedes-benz.com/innovation/case/connectivity... )

I look forward to the old trite HN comment of "I don't want my car to be calling home, I drive a 1980's fully mechanical car and I like it that way!"

Seems ripe for spoofed data. After all, how would you verify that what you receive from other cars is valid/real?

There are a hundred different ways to cause car accidents if that’s what you want to do; this would be adding a single, highly technical one.

In practice, people just don’t do that.

I disagree. Most obnoxious things you can do right now require some sort of physical presence and traceability. You can cause dangerous situations/accidents by blinding people with lasers. You can throw bricks or other obstructions on the highway, and so on.

The problem is that both of these acts immediately pinpoint you (or at least your general location) as the culprit, so it's pretty risky, not just from a law enforcement point of view but also from a "brick in the face" point of view where you might get a taste of your own medicine by the angry driver whose windshield got destroyed by your mischief.

A technology-based attack on the other hand is invisible. By the time someone even uncovers that this was an attack rather than a generic malfunction you're long gone or may not even have been physically there to begin with.

Is that protocol called the brake and signal lights?

Up until Silicon Valley got their hairy hands into self driving tech, there was never a need for such data to be communicated to other *cars* (not drivers).

I wonder if the families of the 19 000 who died in traffic last year in the US alone also consider this a solved problem...

You mean like the traffic monitoring and road hazard reporting of Waze, Google maps Apple maps, etc?

Having a car directly implement that protocol instead of software on an internet connected phone is of limited additional value but adds massive complexity.