The challenge is as old as the stoplight itself: How to time your pace through town so you hit green light after green light, nixing any time spent twiddling your thumbs at red lights. Go too slow, and you’re forever lurching forward trying to squeak through yellows. Go too fast, and you soon reach red lights well before they go green. Get it just right, though, and you dodge the aggravation. You save on fuel, and maybe time. And driving becomes a whole lot more pleasant.

Now, Audi is here to help you master the timing. The automaker announced today a feature that will tell drivers of select models, in select cities, exactly how fast to go if they want to catch nothing but green lights.

The Green Light Optimization Speed Advisory system is an expansion of Audi’s vehicle-to-infrastructure communication system: Since 2016, it has offered “time-to-green,” which tells the driver sitting at a red light how long they have to look at their phone before it’s time to go.

The Green Light Optimization Speed Advisory system calculates its speed recommendation by considering the distance to the next light and the signal timing data. Audi

The feature, which debuted on the A4 sedan and Q7 SUV, is available on every 2019 Audi model, minus the A3 hatchback, TT coupe, and R8 supercar. The light data comes through a partnership with Traffic Technology Services. The Oregon outfit generates the data streams at 4,700 intersections in 13 cities, including Dallas, Denver, Houston, Los Angeles, Orlando, Phoenix, San Francisco, and Washington, DC.

The system calculates its recommendation by considering the distance to the next light and the signal timing data, obtained via onboard 4G LTE cellular data connections. As long as it doesn’t surpass the speed limit, the result is displayed in the instrument cluster or head-up display. Of course, the speed of traffic may inhibit such efficiencies, and there’s no guarantee that other drivers won’t get annoyed when you’re ambling along for a reason they can’t see.

Audi pitches the system as a stress-reduction tool for drivers. It cites AAA Foundation for Traffic Safety data that shows American drivers spend about 300 hours a year behind the wheel. Smoothing out the commutes by allowing them to keep a steady pace can make that time more pleasant. (Massage seats also help.)

Ultimately, such data communication will be essential to the ability of semiautonomous and autonomous cars to achieve one of their key promises: boosting the speed and efficiency of traffic in congested areas. In the rosiest scenarios, the cars will integrate traffic light data with other information from the civic networks and other vehicles on the road to coordinate, optimizing traffic flow. Cars could pace themselves perfectly, even diverting if the traffic grows too dense. That’s all many years away—but even the longest journeys feel shorter when you don’t have to stop so often.

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