The project even has a "like" system that lets drivers say what they think about the cars ahead. It's potentially more effective than honking -- if one driver is routinely cutting people off, all their victims can register their displeasure. The CarNote team even suggests that insurance companies could use an excessive number of dislikes to hike someone's rates. It's hard to say if drivers would agree to that (what if an honest mistake angers a bunch of drivers and ruins your rating?), but it might discourage reckless driving.

It's a clever idea, and early tests suggest that it does lead drivers to be more understanding. However, there are a few challenges to face. At the least, you'd need to build this into most cars to be effective. What good would your built-in AR system be if the person blitzing through traffic is driving a classic car? Also, it'd have to be implemented quickly to make a difference. While we're still years away from fully autonomous cars, they're close enough that CarNote might only be a stopgap that lasts until most cars are smart enough to talk to each other. Still, it's promising -- and it could be worthwhile if it prevents even a few road rage incidents before they start.