New Audi cars can tell you when traffic lights will turn green

A video showcasing the new Audi traffic light tech.

Starting this autumn, when you're stopped at some traffic lights, new Audi Q7 and A4 cars will show a real-time time-to-green-light countdown on the driver's information cluster. Now you'll know exactly when to start revving like a hooligan.

The tech, which Audi has imaginatively dubbed the Traffic Light Information System, receives traffic light timing data via the car's cellular modem. In this case, rather than getting the data directly from nearby traffic lights, the data is being broadcast by some kind of city-wide traffic management system.

As you have probably surmised, there are not yet many of these city-wide systems. Audi says that the green light timer will work in select cities in the US this autumn, but declined to say which cities those might be. UK, European, and Asian cities will surely follow, though no timeline has been given. If you have a 2017 Audi A4, A4 allroad, or Q7 built after June 1, with a cellular connectivity package, you will be able to use the feature (in cities where it's enabled)

Presumably the technology could also tell you if a traffic light is about to turn red. Sadly, the Audi press release doesn't mention whether you'll get an on-dash message encouraging you to speed up so that you can make it through the lights before they change.

Audi's traffic light countdown tech is a small piece of what's generally clumped into the "smart cities" bucket—a buzzword that's been around for a long time now, without much to show for it. As cellular connectivity becomes ever more pervasive, though, and big companies like SAP and IBM begin to provide integrated city management suites, we're finally starting to see some of the myriad benefits that have been enthusiastically waved around by smart city proponents for the last decade or so.

While it looks like Audi will be first with vehicle-to-infrastructure (V2I) tech, the other side of the fence is vehicle-to-vehicle tech (V2V, or sometimes just "vehicle mesh networks"). In this case, Audi gets its information from a centralised system, but with V2V the green light timer could be easily derived from a car in front that reached the traffic lights a few seconds earlier. Likewise, a centralised system is one way to communicate about upcoming accidents, but decentralised V2V—where the data bounces from car to car—is possibly faster and more reliable.

Most major car companies are working on some kind of V2V tech, but as far as we can tell there aren't any production cars with it available. It's probably a classic case of the network effect: V2I only needs a few centralised hubs for it to be useful; V2V needs thousands or millions of other cars with an interoperable comms protocol.

This post originated on Ars Technica UK