During the COVID-19 pandemic, Trump finalized changes to Obama-era automobile emission rules. Whereas automakers were to increase fuel economy by an average of 5% per year through 2026, it was changed to 1.5%. The Trump administration noted that the change would be the equivalent of 2 billion additional barrels of oil consumed and nearly a billion metric tons of carbon dioxide emissions.

The Verge – Trump rolls back Obama fuel economy rule, increasing emissions during a climate crisis
Reuters – Trump finalizes rollback of Obama-era vehicle fuel efficiency standards
The Hill – The pandemic hasn’t stopped Trump’s rollback of Clean Car Standards