• Ford, VW, Honda and BMW struck a deal with the state last summer that bucks the White House effort to roll back Obama-era standards for vehicles built through the mid-2020s.
• "Carmakers that have chosen to be on the wrong side of history will be on the losing end of California’s buying power," Newsom said in a statement on the policy first reported Friday by the site CalMatters.
• That means ending purchases from GM, Fiat Chrysler, Toyota and others siding with the administration in litigation over federal efforts to curb California's power to set rules that roughly a dozen other states follow.
• The important numbers: Per Reuters, California bought nearly $59 million in vehicles from GM in 2016-2018 and nearly $56 million from Fiat Chrysler in the same period.
• Quick take: This is increasingly a game of hardball. Remember the Justice Department recently opened an antitrust inquiry into the four companies that reached the deal with California.

Driving the news, part 2: Electric vehicle makers Tesla and Rivian are joining the fray.

• They're members of the National Coalition for Advanced Transportation — a group that also includes several power and EV charging companies — that has joined litigation on the matter.
• That group filed a motion Friday to intervene in cases filed by California and the Environmental Defense Fund challenging a Transportation Department finding that its purview over fuel economy preempts state tailpipe CO2 rules.
• The group supports maintaining California's standards and zero-emissions vehicles program, and the motion lays out the parties' interests — including Tesla's ability to keep earning valuable compliance credits under the current rules.
• Bloomberg Environment has more.

Where it stands: Those lawsuits, by the way, are two of a growing number in the administration tussle with California. On Friday, California and a suite of other states filed suit against EPA for yanking the state's Clean Air Act waiver to set standards that go beyond federal rules.

Why it matters: It's one of the most intense and consequential regulatory battles of the Trump era.

• Transportation is the nation's largest carbon emissions source. And new Energy Department data shows those emissions rose again last year.
• Meanwhile, automakers want a single set of national rules as they make billion-dollar bets on their future fleets. But the powerful industry has splintered on how to get there and what the standards should be.

Go deeper: The bumpy transition toward electric vehicles

What's next: The study by the congressional watchdog recommends, among other things, that EPA take steps to integrate climate into the Superfund program's risk and response planning.

But, but, but: EPA, in a response included with the report, pushed back against some of the suggestions.

A senior official writes that the program, under existing practices, "adequately ensure that risks and any effects of severe weather events, that may increase in intensity, duration, or frequency, are woven into risk response decisions" for the sites.

Go deeper:

• Why the hottest global warming battle is in the courtroom
• Climate change threatens children's health across the globe
• The trouble with big power companies' net-zero pledges

Context: Under the Obama administration, the U.S. pledged to cut greenhouse gas emissions by 26%-28% below 2005 levels by 2025.

• U.S. emissions of CO2, the dominant greenhouse gas, last year were 12% below 2005 levels, per EIA's report.

The intrigue: President Trump is pulling the U.S. out of the agreement, but the data show how a future president who reverses course would be challenged to meet the existing commitment, let alone a tougher pledge.

What they found: EIA attributed the rise to a warmer summer and a colder winter than in 2017. And then there's transportation, which is the largest source of U.S. emissions and, unlike power, emissions from that sector have been on an upward march.

• "Transportation-related CO2 emissions have been increasing steadily in the United States since 2012 because of a recovering economy and moderate fuel prices," they write.

Go deeper:

• Net-zero carbon pledges are still rare among energy companies
• California, other states sue EPA for right to set higher emissions standards
• Transportation emissions are a tough nut to crack