Brighter, less costly and more efficient, LEDs (light emitting diodes) are making their way into a wide variety of automotive applications, ranging from center high-mount stop lamps (CHMSLs) and turn signals to vehicle cockpits and headlights.

"More and more automotive functions are using LEDs," says Viren Merchant, engineering manager for exterior electronics at Visteon Corp., a tier-one automotive electronics supplier. "In the beginning, it was just CHMSLs. Now it's everything from backup lights to rear fogs to daytime running lights."

Moreover, applications for the technology are growing in unexpected ways. Kia Motors' Soul, for example, has employed LEDs in its sound-reflecting speaker lamp (watch a video of it), which responds with variable light to the beat of the music that's playing on the stereo. And the 2010 Ford Mustang will use an LED-based feature called MyColor, which allows drivers to customize the interior lighting of the Mustang to suit their moods.

Several trends have boosted the popularity of these electronic lights, according to automotive engineers. A few LED products now offer 50 lumens/W – in some cases as much as 100 – whereas many products a few years ago offered less than five. Additionally, electric vehicles and hybrids need power-efficient lighting, which boosts the appeal of LEDs. Meanwhile, the cost of LEDs has gradually dropped over the last five years.

Less than 2 percent of headlights are estimated to use LED technology today. But suppliers say that more than 80 percent of Asian cars use LED-based CHMSLs. Similarly, more than 70 percent of European cars and about half of North American cars are employing LED-based CHMSLs. On the exterior of the vehicle, LEDs are also used in daytime running lamps and parking lights, as well as the high- and low-beam headlights.

Tier-one suppliers say the design flexibility of the LED is a key to its growing popularity. LED packages can be altered to incorporate different numbers of chips, as well as different shapes and sizes. Automakers such as Cadillac, for example, have used that flexibility to create unusually shaped CHMSLs and tail lamps.

In that sense, LEDs are helping automakers create greater brand awareness, in the interior, as well as the car's exterior. Osram, for example, has rolled out LEDs of various colors – including ice blue, blue lagoon, sky blue and blue green – which enable automakers to tune the interior color to match their brand. In an even bolder step, Ford is employing the technology in MyColor, a system that allows drivers to change the interior colors to match their moods.

Tier-one suppliers and LED makers alike say that LED adoption in automotive interiors is growing the fastest of all. "Every interior request for a quote we've received from every manufacturer around the world the last two years has had some aspect of LED ambient lighting to it," Vaughan says.

With the expected proliferation of hybrids and electric vehicles, LED use is expected to grow faster still over the next decade. On those vehicles, where power is at a premium, engineers are more likely to disregard cost differences and reach for LED technology. "It saves about 400-430 Watts of power across the interior of the vehicle, and about 20 Watts on the interior," Godwin says.

Meanwhile, engineers wanting more brightness per W are getting that, too. In April, Philips Lumileds rolled out the Luxeon Rebel ES, claimed to be the world's first high-efficacy power LED specified to deliver a minimum of 100 Lumens per W. The new breed of brighter products is expected to take LEDs into exterior applications, such as red stop lamps, where they've been used sparingly before.

Engineers say that most of the success of LEDs is being realized in luxury- and mid-level vehicles for now. Cadillac's Escalade, as well as selected Lexus and Audi vehicles, are employing LEDs across the board in high-beam, low-beam, daytime running lamps and parking lights. But as prices continue to drop and automakers move to more energy-efficient vehicles, LEDs are expected to migrate toward entry-level cars.