The 2014 Honda Accord Hybrid on Thursday became the latest among a growing list of gas-electric models to take a hit for what critics contend are overly optimistic and misleading mileage claims.
But it's not the first time Honda has been faulted for its hybrid mileage ratings—and the automaker is not alone.
According to Consumer Reports tests, the 2014 Honda Accord Hybrid averaged just 40 miles per gallon in the Environmental Protection Agency's combined city/highway cycle, a full 7 miles per gallon below the figure on its window sticker.
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"We've found that the EPA tests often exaggerate the fuel economy of hybrids," said Jake Fisher, director of automotive testing for Consumer Reports.
In 2012, the publication noted there was a wide disparity between the mileage ratings for the Ford Fusion and C-Max hybrids and what the magazine's test results indicated. Several consumers sued Ford because of that gap. The automaker last year announced it would reduce its stated mileage on the C-Max to 43 miles per gallon.
In Honda's case, the mileage discrepancy can work out to a significantly higher annual fuel bill. At 47 miles per gallon, a typical motorist clocking 15,000 miles a year would expect to burn around 320 gallons annually. At $4 a gallon that would work out to around $1,280. Reduce fuel economy to 40 miles per gallon and the bill rises to about $1,500.
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"The new Accord Hybrid is the most fuel efficient (EPA combined) midsize sedan we've ever made and the most fuel efficient 4-door sedan on the market (EPA-city rating of 50 mpg)," Honda spokesman Steve Kinkade said in a statement Thursday.
"We're very happy to see that in Consumer Reports' testing they confirmed that its 40 mpg average ranks it as the most fuel efficient 4-door midsize sedan they've measured in at least the last 10 years," he said.
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Despite concerns that the industry has been "gaming" the system by tuning vehicles to maximize results in tests, most manufacturers have been sticking by their fuel economy numbers, which are based on testing by the EPA.
—By CNBC Contributor Paul A. Eisenstein. Follow him on Twitter@DetroitBureau or at thedetroitbureau.com.