DETROIT – The Hyundai brand achieved 36 mpg (6.5 L/100 km) corporate average fuel economy in 2011, four years ahead of the U.S. government’s rule for 2016 when all auto makers are mandated to achieve roughly that fleet average in the U.S.

But not all Hyundai car owners are happy with the news.

Hyundai America CEO John Krafcik tells WardsAuto during an interview at the auto show here that the Environmental Protection Agency’s estimated fuel economy of the Elantra compact sedan is achievable in the real world, despite owners who are suggesting otherwise.

Advocacy group Consumer Watchdog petitioned the EPA last month to re-test the Elantra, after some buyers of the current-generation model complained they were unable to achieve the stated fuel economy of 29/40 mpg (8.0-5.9 L/100 km) city/highway.

“We’re not sure who the vocal people are, and who might be representing the vocal people, but we do know this: In a very large (sample) survey by J.D. Power of 2011 car buyers,” the Elantra got better real-world fuel economy than any other competitor, Krafcik says, citing the analytic firm’s APEAL study that measures satisfaction in the first 90 days of ownership.

“I don’t fully understand some of the accusations, but part of it is due to the fact we’re doing better in the marketplace now, and people are aware of and know Hyundai a little bit better than they did a few years ago,” he says. “Probably every car in every car maker’s lineup has people complaining about the real-world fuel economy they’re getting.”

Hyundai is reaching out to unhappy Elantra customers via its dealers to better understand their driving patterns and help them increase fuel efficiency.

“Typically, what we find is these are urban drivers who have a lot of time, much more time than they realize, just sitting and idling at a stop sign,” Krafcik says. “When we show them that’s much more severe than the EPA city-cycle, and that here are some tips on how you can drive the car, the light bulb goes off.”

Hyundai is debuting its Veloster Turbo and refreshed Genesis Coupe at the show here. Other new models due from the brand this year include a next-generation Santa Fe cross/utility vehicle.

Hyundai's U.S. sales rose 20% in 2011 to 645,691 units, WardsAuto data shows.