The Accord offers multiple versions including gas, hybrid and electric, and even the largest petrol engine V-6 model gets an impressive 34 miles per gallon (mpg) for highway driving.
Its rivals for the yesterday's environmentally-friendly prize, announced the day before the LA show opens to the public, were the Audi A6 TDI, the BMW 328d, the Mazda 3 and the Toyota Corolla.
"The diversity of this field of finalists illustrates not only that green has gone mainstream, but also that there is no single approach to achieving ever-higher levels of fuel efficiency and environmental performance," said Ron Cogan, publisher of Green Car Journal, which hands out the prize.
"It's accommodating, featuring the comfort and functionality expected of a mainstream sedan and incorporating the latest in on-board electronics and safety systems, although while delivering a satisfying driving experience."
"Importantly it excels with the versatile approach to environmental leadership."
American Honda senior vice president Mike Accavitti said the car "offers something for everyone," adding that the green prize highlights "our shared vision of the future of low and ultra-low carbon emissions."
Last year's award was won by the Ford Fusion, following the Honda Civic Natural Gas and the Chevrolet Volt in previous years.
The LA Auto Show opens to the public today after three press preview days, and wraps up on December 1.