LIGHTING is the stuff of drama, in cars as well as on stage.
More and more, dramatic lighting seeps from under dashboards and seats or gives a glow to the door sills. The 2013 Cadillac XTS has illuminated exterior door handles. A glowing ring surrounds the recharging port of the Ford Focus Electric. Open the door of a new Ford Mustang or Range Rover Evoque at night and "puddle lamps" project the maker's logo on the ground, like the Bat-Signal beamed onto clouds.
Lighting is growing in its role as the new face of auto style and branding; manufacturers are shaping headlights to help establish a signature for their brands, much as grilles' shapes have in the past. The main headlamps and high beams, daytime running lights and turn signals have become increasingly complex parts of cars' faces.
As new technologies arrive, designers say, lighting more and more plays the stylistic role once performed by chrome and glass.
In presentations at auto shows and in online videos, the Mercedes-Benz design chief, Gorden Wagener, described the headlight of the Concept Style Coupé, first shown in Beijing in 2012.
"For us the light is always based on something human, the eye," he said. "The brow is the daytime light, and the lid moves up for the brights."
Audi was a pioneer in bringing LEDs -- light emitting diodes, a more efficient and longer lasting replacement for conventional bulbs -- to automotive lighting and in using them as a styling element. Audi's lighting design, however, is unabashedly mechanical, rather than biological, in its style.
"Our slogan is 'progress through technology,' " said Cesar Muntada, an Audi exterior designer who works on lighting, "so the key to all Audi design is giving the purest expression of that technology.
"We want an Audi to be as recognizable at night as it is during the day," Mr. Muntada said in a telephone interview. "We always use the system that performs the best. We have taken something functional and made it an aesthetic."
The company is constantly incorporating novel technology in its lighting, Mr. Muntada said. Audi first used LEDs in daytime running lights, arrayed in a simple bar of distinct lamps. Now, more sophisticated designs distinguish Audi models. In the latest generation of Audi headlights, low- and high-beam LEDs are separated, and the running light doubles as turn indicator.
In contrast to Audi's modernist form-follows-function approach, Lincoln's designers are looking for less complex light designs.
Lincoln's theme these days is elegant simplicity, said Solomon Song, chief exterior designer of the 2013 MKZ midsize sedan. The car's strikingly thin headlights follow that idea.
"If you look at a lot of cars on the road today, their headlights are getting bigger and bigger," Mr. Song said in a telephone interview. "There's a lot to cram in.
"I didn't want that; I wanted the aesthetics of the slimmer headlamp," he said. "It's just a pure sculpture. We let the headlamps do the talking."
Mr. Song also worked to differentiate between the style and the function of the lights.
"We didn't want to meld the sculpture and the functional elements together," he said, "but to keep them separate."
He compared the split of function and style to a watch: "If you look at a fine watch, all you see immediately is the art. You have to look inside or in back to see the mechanical elements."
The operation of LEDs can affect the styling of the lamps. Mr. Song said that one lesson learned while developing the MKZ was that because LEDs generate less heat, they will not melt snow and ice on the front of the car in the same way.
"There's no heat circulation," he said. "So we have a rear heat sink and had to install fans in back."
Technologies of the future, he suggested, will change headlamps again. "Lasers are more efficient and get superbright, but take a bigger headlamp," Mr. Song said.
BMW's round lamps are almost as distinctive a symbol of the brand as its so-called kidney grille. But the lamps have been interpreted in different ways with succeeding technologies.
Sebastian Morgenstern, an exterior detail designer at BMW, noted the evolution of the brand's characteristic double round headlights in a video the company posted online.
The round format arrived in the 1960s, he said, but did not become strongly linked to BMW until the 1980s, when most other marques moved toward more square or oblong lamps. The round headlights are always surmounted by a lidlike structure, giving the face of the car an intent, even predatory, expression.
"The critical thing is to cut the circles at the proper angle," Mr. Morgenstern said. In 2000 came coronalike lamps that advanced the dual circle theme. Now LEDs are used in the 6 Series, and the round lamps are replaced with angled, three dimensional versions of their shapes.
"The new technologies give designers new possibilities," Mr. Morgenstern said.
The newest Range Rover updates the complex overlapping circles of earlier models with new LED blade technology. Done under the supervision of Gerry McGovern, the design plays a change on what he called the interlocking forms of earlier Range Rovers. These had a technical look, suggesting lenses packed tightly together.
"The front lamps continue the evolution of the Range Rover face," he said in a description of the new design. "Distinctive signature lighting graphics use LED light blade technology, showcasing the hallmark interlocking circle design." The primary lamps, the projector beams, were designed to resemble a camera lens, he said.
This article originally appeared in The New York Times.