The quest for better fuel economy has General Motors cribbing from headphone technology.
The boost the efficiency of the GMC Terrain crossover utility vehicle, engineers bolted a six-speed gearbox to the 2.4-liter direct-injection four-banger. It sports an "eco model" that lowers the shift points, squeezing another mile or so from a gallon of gas for an EPA-rated 32 mpg highway. Trouble is, running in eco mode created an intrusive and annoying low-frequency hum.
To counteract the boom, they installed an active noise canceling system similar to what's found in many headphones. Honda has used the technology in the past, and Infiniti uses "Active Noise Control," to minimize the sound of the exhaust at low engine speeds. BMW reportedly is considering the technology for use in diesel models.
When the two microphones in the headliner detect the hum, a frequency generator emits counteracting sound waves through the audio system’s speakers and subwoofer. The system also helps keep things quiet at higher RPMs when cruising at highway speeds.
Although the Terrain is the first GM vehicle to use the technology, it could appear in other models.
“It has strong potential for implementation on other four-cylinder vehicle programs," Paul Beaker, Terrain program engineering manager, said.
UPDATED 2 p.m. and 8 p.m. Eastern February 23.
Image: General Motors
