The move is said to be focused on preventing automakers from using computer modeling or lab-test manipulation to exaggerate mpg claims. The agency has received complaints from many drivers who achieve real-world mpg figures that are significantly lower than manufacturer claims.
Several automakers have been forced to revise their mpg ratings for existing models. Notable cases include a handful of newer models from Hyundai, Kia and Ford.
“Some auto makers already do [real-world verification], but we are establishing a regulatory requirement for all auto makers,” EPA Office of Transportation and Air Quality director Chris Grundler told The Wall Street Journal.
The greatest discrepancies between mpg estimates and real-world performance have appeared in hybrid models. Ford’s 2013-2014 Lincoln MKZ Hybrid is a glaring example, with a recent revision dropping its city/highway mpg estimates by 7-8 mpg.
Ford blamed its error on incorrect rolling-resistance figures that were correlated to wind-tunnel observations when determining mpg estimates. The EPA proposal aims to force companies to compare their computer-modeled variables against observations from real-world testing on a track, verifying figures for wind resistance and rolling friction.
The EPA is preparing to accept public comments on the proposal before moving forward with implementation.
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