Anytime I hear V2V described it sounds like some sort of throwback to the 1990s, like before cellular networks and the Internet became pervasive. I don't understand why they want to invent this completely new communications infrastructure and waste a ton of spectrum on it.
Because without an inherently untrusted and untrustworthy system for allowing one vehicle to scare another vehicle into doing something dangerous, the rise of autonomous vehicles will make it almost impossible to commit political assassinations by causing car accidents. Only if a communication system makes it possible to hack another vehicle or otherwise convince it that there is some obstacle that it absolutely must evade quickly can you feasibly trick two vehicles into crashing into each other in a way that would cause one of them to flip or drive off an embankment.
Whoops. Did I say that out loud? What are those black vans doing outside?
But in all seriousness, every time I hear "V2V", I immediately think "clueless politician who doesn't understand computers or computer security," and then the insanity suddenly makes a lot more sense. To someone who doesn't understand computers, the idea of one car being able to communicate risks to other cars in the fleet sounds like it should be a good idea.
The problem is that V2V can't feasibly cause a computer to react sooner than when it sees the brake lights of the car in front of it, and unless vehicles are tailgating (translated "being driven by humans"), it shouldn't matter if the vehicle two cars ahead has to brake, because there should be enough time for the message to propagate via a chain of brake lights. Therefore, there is no feasible scenario where V2V could prevent even one accident per year, much less 439,000 accidents per year.
Okay, maybe, just maybe you
might occasionally be able to warn about black ice in some spot, and if vehicles aren't programmed to slow down in curves when the temperature is at or below freezing, then maybe,
maybe you might occasionally prevent an accident or two, but only in a very narrow time window, and only if you have a near continuous flow of cars behind you, all within range of the V2V system. Of course, if you have that, chances are you also won't have black ice accumulation, because it tends to mostly form on roads that are not heavily traveled. After all, within minutes, that car will reach a non-cellular-dead zone and could communicate that information in a much simpler fashion using existing hardware, where any other car in the fleet could pick it up and remember it for when it enters that area in the future. So maybe single-digit accidents? Maybe even double-digit?
So basically, that fairly significant extra amount of engineering and the significant extra hardware costs (not to mention extra points of failure) would add almost no additional safety, in practice. It would, however, create an amazing opportunity for hacking and malicious mischief. It's a security hole so big that you can drive a truck through it — literally, if you try hard enough.
But if you assume that the person suggesting it still thinks that the Internet goes down whenever his/her cable line gets corroded, still uses the phrase "world-wide web", calls email messages "internets", and just got his/her computer de-virused for the fourth time this month, you can at least understand why such a person would want to mandate such a disaster waiting to happen.
I like it from the standpoint of toll collection in that it gives toll operators a single standard to toll versus many standards.
I also like it from the standpoint of adding intelligence to stop lights. Everything from letting the car known how long the green will be (to optimize speed) to better traffic management.
Both of those are technically I2V/V2I (infrastructure to vehicle/vehicle to infrastructure) communication. And as long as it is being used exclusively in an advisory fashion (to optimize speed), with primary detection done optically, the risk introduced is probably pretty small. Of course, once all vehicles are autonomous, traffic lights likely won't be needed anyway, so I remain unconvinced.
And paying tolls with toll tags is cheap, doesn't require any changes to vehicle hardware, and doesn't introduce any security risks. I can't see why anyone would willingly make that be part of the vehicle. Also, the tracking concerns with doing so are pretty significant.