EPA: Fuel efficiency dropped in 2019

The average fuel efficiency of cars and light trucks sold in the U.S. dipped in model year 2019, newly released federal data shows.

Why it matters: Transportation is the nation's largest source of greenhouse gas emissions. The overall trends (see above) show that the sector is far from steep emissions cuts.

How it works: Per Reuters, "The shift to larger vehicles was the biggest factor hurting fuel economy. In 2019, 44% of the fleet were cars and 56% were light-duty trucks, a category that includes SUVs, the highest percentage of trucks on record."

What they're saying: EPA Administrator Andrew Wheeler said the data justifies his agency's decision to weaken Obama-era rules on mileage and CO2 emissions to allow smaller increases through the mid-2020s.

• "This report shows in detail how few auto manufactures were able to meet the unrealistic emissions standards set by the Obama administration without resorting to purchasing emission credits," he said.

The other side: Dan Becker, an advocate for much tougher emissions standards, said the data show why the incoming administration must reverse Trump policy.

• "Without tough rules from the Biden administration, automakers will keep pushing gas-guzzling Trumpmobiles on consumers rather than deliver clean cars that cut pollution," said Becker, who's with the Center for Biological Diversity.