The Obama administration tightened fuel-economy requirements

https://obamawhitehouse.archives.gov/the-press-office/2012/08/28/obama-administration-finalizes-historic-545-MPG-fuel-efficiency-standard

https://www.politico.com/story/2016/08/obama-tightens-fuel-efficiency-rules-for-trucks-227059

Trump was elected. The Trump administration killed Obama's measures:

https://abcnews.com/Politics/epa-administrator-scott-pruitt-announces-rollback-obama-era/story?id=54202466

https://www.washingtonpost.com/local/trafficandcommuting/trump-administration-rolls-back-rules-on-mileage-standards-dealing-a-blow-to-obama-era-climate-policy/2020/03/31/cb42cbb8-7359-11ea-87da-77a8136c1a6d_story.html

Joe Biden was elected. Biden tightened fuel-economy requirements:

https://nam.org/biden-administration-finalizes-fuel-economy-standards/

https://apnews.com/article/climate-joe-biden-fuel-economy-vehicle-mileage-standards-348bb3368036eb504f3b138a680739c7

Donald Trump was elected. The Trump administration killed fuel-effiency rules again :

https://www.theguardian.com/us-news/2025/dec/03/trump-fuel-efficiency-rules

Most americans don't pay attention, but it's just insane.

Unfortunately, the U.S. car norms influence Canada. Because Canadian officials copy american car norms. It's the reason why they drive the heaviest and least efficient cars in the world

https://theconversation.com/when-it-comes-to-vehicles-canada-tops-the-charts-for-poor-fuel-economy-115213