It is now getting to the point that there are enough self driving cars on the road that should be encountering each other. Accidents happen when one vehicle does something the other is not aware of or is not expecting.

The last collision I am aware of between two autonomous vehicles was the in the 2007 DARPA challenge between Cornell & MIT. It would seem to be common sense that if cars are talking to each other and the potential for accidents between them would drop significantly.

Do self driving cars talk to each other?

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    I don't have anything definitive, but would bet the answer is no. This would be due to three reason: 1) Autonomous car being so new; 2) Only a handful of functional ones; 3) No specifications for it yet. Commented Sep 22, 2016 at 16:48
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    Back in 2014, the NHTSA made a press release that they were looking at requiring car-to-car communication in the future, but I'm not sure if anything ever came from that.
    – JPhi1618
    Commented Sep 22, 2016 at 17:24
  • Since the 60-70s car to car communications has been talked about and was the future that was coming. 2011 was to see DOT award 14 million to make car to car research and development happen. It is not just self driving cars that need it, if it is to do any good all cars need to be in the loop. But do not expect anything serious toward this until about 2025 Commented Sep 22, 2016 at 17:52

2 Answers 2


Update, Dec 2016: Just this month, Michigan legalizes self-driving car testing on public roads, and GM is going to start testing. As things continue to move in this direction, the field will no doubt start to lend itself towards developed communications protocols.

At the same time, also this month, the NHTSA is pushing to move forward with deployment of mandatory V2V protocols, which ultimately will make the answer to "Do self driving cars talk to each other?" a solid yes.

Like I said below, we're right on the cusp of this technology. It will happen.

From Sep 2016:

The short answer is: Not yet. But eventually.

Right now, I know the Teslas don't. AFAIK the Google ones do not either.

First of all, some concrete info: At least as far as the NHTSA is concerned, a few years ago they started murmuring about a potential vehicle-to-vehicle communications standard, at least in the US (V2V). The project web site is at http://www.safercar.gov/v2v/index.html and you can check there for updated info. At the time of this writing, the latest development is that meetings are still being held and the project is still in the assessment and planning stage. A recording of that meeting from April 2016 is available. This means that at least in the US, there currently is no standard communications protocol for it.

On the more conceptual side: Ideally, you would not want self-driving cars to have to talk to each other in order to maintain safety in today's conditions, because most cars are not self-driving. Ideally a self-driving car should avoid collisions with other vehicles and objects on the road, regardless of whether or not those other vehicles are also self-driving -- it shouldn't have to know or care what's controlling other vehicles. That is, other vehicles are simply other vehicles to be avoided, rather than special cases.

This means that, at least today, if a self-driving car was unable to reasonably avoid collisions with another vehicle unless it was also explicitly communicating with that other vehicle, then really that car would not be suitable for safe road use.

You also don't want to rely on it because if e.g. there's some atmospheric interference or damage to the communications, you don't want cars to no longer be able to avoid collisions.

Also, in the future, at least IMHO, car-to-car communication would be extremely desirable not just for collision avoidance but for traffic management as well. For example, here is a video discussing autonomous traffic management protocols, as well as the home page of that project which contains many interesting references. The page is a bit old and some links are broken, I remember they used to have a simulator, circa 2004, but I can no longer find it, not even on archive.org. But, I digress...

There's still a long way to go to get the vehicles to be as safe as possible on their own, and there's really not a lot of them. Autopilot now still relies on a lot of care and monitoring on the part of the driver to maintain safety; for example, here is a video of a complete 45 minute commute with a Tesla system, driven by an attentive and responsible driver who understands its limitations (example), with commentary along the way. It's a long video, but a fascinating look at the current strengths and weaknesses and a good look at what autopilot is currently like for the vast majority of us who don't own these cars ourselves.

All of this technology has been in people's minds for a very long time; we've got the building blocks now (well-developed machine vision algorithms and such) and it's only relatively recently that the self-driving and control algorithms themselves have gotten to the point where we can start using these cars on the road. The basics are in place, but still need polishing, one step at a time. The current focus is just getting these vehicles functional, but discussions are certainly underway about vehicle communications in the future, because the need for that is now just around the corner.


The short answer is that they don't yet talk to each other (why would they as there are so few self-driving cars on the road currently, so the chances of two meeting are practically zero?), but will definitely do so in the future. In fact, my dayjob is developing 5G mobile networks, and one of the potential applications of 5G is communication between cars (self-driving or not).

One of the improvements of 5G networks will be lowered latency, which means that e.g. a car can signal that it's doing an emergency braking procedure, and other cars in the vicinity will realize it within a millisecond or so. Much better than human reaction time which is about a second. Actually, even the 4G latency of about 10 ms is better than the human reaction time, but if we can improve things, why not improve them?

Of course, it's not certain that 5G will be the selected mechanism for vehicle-to-vehicle communication. It is also possible that a communication mechanism not employing a base station will be selected.

You can expect 5G networks to be deployed starting from approximately the year 2020.

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