Audi A8s sold in Europe include some clever lighting systems -- systems that Audi is struggling to get U.S. regulators to approve. Photo credit: Audi

If you pay attention to trends in new-car design, it has been hard to miss this trend: distinctive use of lights, particularly LED lights, as trim. Most credit the trend to Volkswagen's(VWAGY -1.13%) Audi brand, which kicked it off a few years ago -- but many other automakers have since jumped on the trend.

To name just one: Cadillac. The Motley Fool was in attendance when General Motors (GM -0.04%) took the wraps off its all-new Cadillac Escalade this past week. We noted that GM's new luxo-truck features all sorts of innovative lighting touches, including the very elaborate headlight system pictured below.


The 2015 Cadillac Escalade's elaborate headlights. Photo credit: General Motors Co.

But Audi continues to raise the bar. Its refreshed A8 sedan includes several new lighting ideas, including the sequential turn signals illustrated in this series of photos. But the A8s sold in the U.S. lack several of these features. Why?


Will the Audi A8's distinctive turn signals come to the U.S.? Photo credit: Audi

As Fool contributor John Rosevear explains in this video, the problem is that U.S. regulators have put the kibosh on several of Audi's latest innovations. Watch as John explains what the problem is -- and how Audi, and other automakers, are working to get around it.