Thus far, automakers appear to have had little trouble meeting the corporate average fuel economy rules that started for 2012 vehicle and will rise steadily through 2025.

The general consensus so far is that carmakers have been able to raise their EPA ratings with a combination of tactics that largely didn't require more expensive hybrid or diesel powertrains in passenger vehicles.

But now the EPA itself may be starting to consider whether the surging popularity of heavier, less aerodynamic utility vehicles over sedans may throw a wrench in the works.

DON'T MISS: Fuel-Economy Rules Likely To Stay Put Through Midterm Review: Consensus

A recent article in The Detroit News suggests for the first time that the EPA might consider changes to the final set of efficiency rules, set to take effect for cars in model years 2021 to 2025.

While government officials remain "cautiously optimistic" that carmakers can meet the current standards, they acknowledged that the upcoming midterm review of the standards will have to look at vehicle mix and the popularity of SUVs of all sizes.

The rules in place today require a CAFE of 54.5 miles per gallon, which in the arcane math of such regulations, translates to roughly 42 mpg for the combined fuel-economy rating seen on new-car window stickers.

2014 BMW i3 range-extender EPA window sticker (Image: Tom Moloughney)

2014 BMW i3 range-extender EPA window sticker (Image: Tom Moloughney)

The News interviewed Kevin Green, the CAFE program chief at the National Highway Traffic Safety Administration (NHTSA), following an Automotive World Megatrends USA presentation in Dearborn.

Green told the newspaper that the mandatory midterm review of the standards, to be conducted next year, must be based on the latest data on market trends and progress to date.

Representing the interests of automakers, a spokesman from the Alliance of Auto Manufacturers pointed out that carmakers have to build what their customers want to buy.

ALSO SEE: U.S. Will Meet Fuel-Economy Goals Despite Higher Truck, SUV Sales, EPA Says

“These vehicles have to be sold," said Chris Nevers, director of climate and fuel economy for the alliance, "not just produced.”

The midterm review includes several steps. First, the agency will issue a technical assessment report by June 2016, on which the public may comment.

Then it will make a preliminary determination, followed by a final ruling on whether to change the standards, by April 2018 at the latest.

Old Gas Pumps

Old Gas Pumps

Because automakers must set long-term technical strategies and make investment decisions years before specific cars come to market, three years is actually a short period before 2021 model-year cars go on sale.

While we're not predicting an outcome, the unfolding drama will clearly follow a known script.

In general, automakers and their lobbyists will push for the standards to be relaxed, delayed, or altered in detail to make achieving them less costly.

MORE: Should Safer Cars Get Credit For More MPG? Automaker Trade Group Says Yes

Environmental advocates and consumer groups, on the other hand, will suggest that the standards are achievable, that the industry has proven its flexibility and capability in doing so thus far.

Furthermore, those parties will say, any changes to the standards would represent dangerous backsliding on a commitment to save buyers money and slash greenhouse-gas emissions from private vehicles.

Get some popcorn and pull up a chair.


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