It’s an unspoken rule of automotive journalism that every major automotive expo has to be defined by an overarching theme, albeit it can sometimes feel like these themes are artifices delivered subjectively by automotive journalists themselves.  

The theme of the 2014 Detroit Auto Show, which opens to the public on Saturday and runs through Jan. 26, has been defined by many in the automotive press as a show about high performance and high horsepower.

“Power is back in vogue,” gushed Fox News writer Doug McKelway, as if power had ever gone out of vogue.

Theme or no theme, one detail was notable across the spectrum of vehicles on display at the show: that the modern car headlight has come of age, especially ones with Light Emitting Diodes, or LEDs, which only a few years ago were uncommon but are now are ubiquitous in luxury brands like Audi and Cadillac. They’re expensive and complicated to engineer because LEDs have to be shielded from temperature fluctuations that can affect the intensity of the light they emit. While still roughly twice as expensive as xenon lamps, the price of LED technology is falling fast and starting to show up in mass market vehicles, such as the 2014 Toyota Corolla.

Part of the reason is that manufacturers such as Osram Licht AG (ETR:OSR), a leading innovator of lighting systems based in Muenchen, Germany, have been developing lower-cost generic LED components for autos, interior lighting and consumer electronics. The company predicts in a report last fall that one in five headlights manufactured by 2020 will be LED-based, a tenfold increase from last year. Market research firm TechNavio estimates that traditional halogen lamps -- still the most common type of vehicular headlight globally -- will grow about 1.2 percent a year through 2018 as they continue to be used in lower-cost cars and trucks. The heat generated by these bulbs compared to the newer technology will continue to pose a challenge to growth, it added. Essentially as LEDs get cheaper to produce, the halogen advantage will diminish and inevitably disappear in the long run just like those ancient carbide lamps that used to light the way of early horseless carriages.

The U.S. has traditionally fallen behind in the development and deployment of newer headlight technology because the regulatory oversight of headlights has been slower to embrace innovations than in Europe and Asia. Rules defining automotive manufacturing standards (which since the late '70s has been administered by the National Highway Traffic Safety Administration) had regulated even the shape of headlights. Those boring old round sealed-beam halogen headlights continued to be the norm in U.S. vehicles long after the Europeans and Japanese began shifting to more innovative approaches, such as the covered faired-in headlights that date as far back as the 1961 Jaguar E-type. For decades, U.S. car designers were basically stuck with what was basically a choice between two 7-inch or four 5-inch filament-burning light bulbs. They weren’t even allowed to be rectangular shaped until the '70s.

Because of this history, U.S. autos have lagged behind in the introduction of two primary new kinds of illumination: High Intensity Discharge (HID) arc lamps and LEDs. HID lights are typically illuminated by xenon-gas filled capsules illuminated by high-voltage electrical nodes. LEDs emit less-intense light than HID lamps but also use less energy and are more easily articulated into design signatures.

LEDs in particular can be integrated into almost any part of a car and have become an aspect of vehicular design language. Volkswagen’s LED “dots” that ring the outer rim of its headlights in its newer models is a good example of how automakers using LEDs to give their headlights a brand signature. Not everyone is pleased with the use of LEDs as a brand-identity element. “Headlight mascara,” is how Hooniverse automotive writer Robert Emslie described Audi’s signature headlight styling, describing the shape of the lines as looking like the cars had a stroke.

The way the light is cast in front of the vehicle, known as beam shaping, has also come a long way since the 1980s when lenses were placed in front of filament lamps to direct more of the light where it was most needed: downward onto the road in front of the car. Rear reflectors behind the bulb were then added to help shape the light. By the end of the '80s, headlight leveling, the mechanism that keeps the beams pointing forward when, for example, a car is loaded heavily in the back causing the front to point upward, was commonplace.

Adaptive headlights, which points the light in the direction the driver is steering he car toward, has been around since the '50s without much success because of the complexity involved with using tiny motors to physically move the light bulbs. In the past decade, actuators have been developed that allow the source of the light to remain stationary while reflecting the light itself in different directions. Adaptive headlights are now standard features in many luxury cars, though there is some debate as to their usefulness. Another common feature in both mass market and luxury autos are projector lenses, basically a convex piece of glass in front of the arc bulb with an adjustable shield between them to switch between low and high beams.

The latest technology just now coming to market at BMW are laser lights, which work by beaming a laser back toward tiny mirrors than bounce the light forward and can provide highly precise beams that can be adjusted automatically or on the fly. These lamps use less energy than LEDs and offer a wide array of possibilities, such as lighting up the ground around the front end in the event of a roadside breakdown.

Audi is taking the idea of beam shaping a step further with its LED-based matrix beam lights that illuminates the entire road but automatically dims the light in specific areas when it detects oncoming vehicles. In other words: no more choosing between high and low beams. This pricey option is already available in Europe, but, like the decades-long ban in the U.S. on anything other than sealed-beam headlights, Americans will have to wait until regulations that require high and low beam options are changed.

The latest in headlight articulation and development doesn’t matter to most auto buyers. Like other automotive innovations, these features are introduced at the high end of luxury first before trickling down to the mass market. The first of the latest raft of headlight technology to start appearing in cars most people can afford is LED. And the diversity of headlight design seen at the 2014 Detroit Auto Show is certainly one of the more noticeable themes this year.