Back in the 1980s headlight companies developed sealed reflector/lens assemblies that permitted replacement of the bulb. This was a breakthrough: Not only were the replaceable-bulb halogens brighter than the older style of light, but they also meant that burning out a bulb didn't have to mean replacing an entire assembly.
There was just one problem: Federal rules demanded "sealed beams" or all-in-one headlight assemblies with a nonreplaceable bulb inside. It took until 1984 for American drivers to get the better headlights they wanted while regulators got a grip on the notion that the bulbs should be replaceable.
It should come as no surprise that technology is transforming cars much faster than stodgy government rules can adjust. More recently, laws specified the wattage of bulbs for taillights and other lights. LEDs use much less power than incandescents and didn't meet that requirement even though they were as bright or brighter than the old filament-based bulbs, so those regulations had to change.
As the pace of innovation accelerates, the gap between invention and regulation widens, making it unclear whether some of the coolest new automotive tech will actually be allowed in American cars. These clever car systems, unfortunately, are having a hard time getting approval in the U.S.
Dynamic High Beams
New headlights use arrays of LEDs that can be programmed to pinpoint where light goes. In the case of Audi's Matrix Beam Lighting and BMW's Dynamic High Beam, for example, when another car approaches, headlight arrays dim only the specific LEDs that shine into the oncoming lane. Volvo's Active High Beam Control uses a conventional light matched to a computer-controlled blind that shields your headlight beam from an oncoming driver's eye.
These systems let drivers enjoy the benefits of bright illumination without blinding the oncoming driver. Currently, though, the federal vehicle safety code permits only one kind of low beam, the kind that dims all of the high beam elements on both sides of the car.
Dynamic Light Spot
Mercedes has a lighting technology that identifies pedestrians on the shoulder or sidewalk via an infrared sensor and shines a light on them. This jibes with American laws, and Mercedes sells it on cars in the U.S. The next step is spotlighting pedestrians if they step into the street. BMW's Dynamic Light Spot system will do just that, but the option is not available in the U.S. for the same reason we can't have dynamic high beams.
Strobe Brake Lights
Mercedes-Benz sells cars in Europe that are equipped with brake lights that flash quickly in response to hard brake pressure. The idea is to warn following drivers of a sudden stop from cars ahead. But U.S. government regulators say brake lights are allowed to do only one thing: glow more brightly than the taillights. Flashing is off-limits. Mercedes did get approval to install the feature on a few cars, as a trial program, but that's all.
Dual-View Front Video Display
In some cases, technology might pass muster in Washington but fail in the statehouse. That's the case with the Mercedes-Benz Splitview system, available on the S-Class and CL-Class, which lets the central display screen on the dashboard show navigation, infotainment, or other typical information for the driver while simultaneously showing a movie or other entertainment for the front-seat passenger.
Mercedes can't sell cars equipped with Splitview in Massachusetts, Pennsylvania, West Virginia and Wisconsin, because the laws in those states prohibiting front-seat video haven't been refined to apply to only the driver. They were written with the assumption that an image on the screen would be the same for viewers in both front seats.