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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.





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Rear-View Mirror Cams



Another video screen that regulators don't like is one that shows the image that we'd normally see in the rear-view mirrors. So while Audi likes to introduce into its production cars technology used on its famous Le Mans–winning race cars whenever possible, don't expect to see the bright, organic LED display showing the view behind you to pop up on your next S5 or R8. Video screens that show moving images while the car is moving forward aren't allowed.







Remote-Mount Magnetic Camera



Land Rover used to offer a nifty magnetic-mount video camera that streamed live images to the dash display. Off-roaders could stick the camera to any steel surface on or underneath the Land Rover, providing an electronic spotter for off-road trail obstacles that can't be seen from the driver's seat. This, too, is forbidden on U.S. roads.













Lightweight Seats



Sometimes, the regulations change but the products don't. Porsche has traditionally offered optional lightweight seats in other markets that let fanatical owners shave weight. But the carmaker dropped the sport bucket seats for the 911 in 2011 because the seats couldn't meet more stringent crash safety requirements. The issue persists today, not just with the 911, but other high-end sports cars like the AMG models from Mercedes-Benz—many of which offer a lightweight seat in Europe but not on our side of the pond.





Aspherical Mirrors



On an aspherical mirror, the main part of the mirror surface is flat, but it curves away toward the outer edge to show all the space in your blind spot. These helpful features remain illegal here because of bureaucratic foot-dragging in Washington. A 2007 law required the Department of Transportation to revise the federal vehicle code to require a larger field of view in the mirror by the end of 2012, but that new rule—which could permit aspherical mirrors—still hasn't arrived. For now, we're still stuck with flat driver's-side mirrors.





Remote Start



To be fair, we do get some things here that other countries don't get. One of them is the winter-weather godsend of remote start. General Motors and Chrysler are particular proponents of factory-installed remote start, but they don't offer the feature in other countries. Why not? Bureaucrats are the same everywhere, and a feature that Batman would have on his car just seems too, well, excessive to them.



So, while we can warm and de-ice our cars from the comfort of our breakfast table, our European friends get to freeze their fingers scraping ice and gripping a cold steering wheel. There, laws in some countries prohibit idling an empty car in a bid to minimize carbon dioxide emissions.



[Related: 101 Gadgets That Changed The World]

