President Donald Trump has essentially killed all fuel economy rules on cars and trucks in the United States. By the end of the year, automakers will face virtually no limits on how many huge gas guzzlers they can sell to the public — or what those purchases will do to domestic oil prices. But is the thinking driving this change up to date?

Rob is joined by Kenneth Gillingham, a professor of environmental and energy economics at Yale. They chat about how the economics profession changed its mind about fuel efficiency rules for cars and trucks — and then recently changed its mind again. They also debrief about what the Trump rollback gets right and wrong in its key economic assumptions and how that might affect its reception.

Then Rob chats with Hannah Hess, an associate director from the Rhodium Group about new Clean Investment Monitor data that shows the U.S. clean energy economy was a “tale of two industries” in Q4 2025.

Shift Key is hosted by Robinson Meyer, the founding executive editor of Heatmap News.

You can find a full transcript of the episode here.

Mentioned:

From Heatmap: Trump’s One Big Beautiful Blow to the EV Supply Chain

Clean Investment Monitor’s U.S. Q4 2025 Update

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This episode of Shift Key is sponsored by ...

Accelerate your clean energy career with Yale’s online certificate programs. Explore the 10-month Financing and Deploying Clean Energy program or the 5-month Clean and Equitable Energy Development program. Use referral code HeatMap26 and get your application in by the priority deadline for $500 off tuition to one of Yale’s online certificate programs in clean energy. Learn more at cbey.yale.edu/online-learning-opportunities.

Music for Shift Key is by Adam Kromelow.

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