Vehicles from Honda and other automakers passed the same EPA tests that revealed Hyundai and Kia had overstated their fuel economy ratings on 13 nameplates in the 2011-13 model years, industry sources say.
The EPA this month ordered the two Korean brands to relabel the affected vehicles with lower fuel economy numbers.
Hyundai and Kia, which face lawsuits and will voluntarily spend millions of dollars reimbursing customers for extra fuel, said the errors stemmed from how engineers in Korea conducted the "coast down" test, a main step used to calculate U.S. fuel economy.
Industry sources say the EPA has replicated the coast down test since 2010 to check more than a half dozen automakers' math.
The companies include Honda North America Inc. and Toyota Motor North America Inc., both of which confirmed the audits to Automotive News.
Honda says the EPA told the company it was satisfied with fuel economy claims for the 2011 Accord and 2012 Civic.
"Our numbers did check out," said Edward Cohen, vice president of government and industry relations.