Cars and trucks are getting bigger, and I had a vague sense that fuel economy regulations were partly to blame. Looking into it, it's hard to say how much is regulations vs people wanting to buy vehicles that look rugged, but the regulations really aren't helping.

This chart is the core of it:

This is what manufacturers were looking at when they decided to build today's cars. To figure out the target fuel economy for a vehicle you first calculate its "footprint", which is the area between the wheels. On our 2013 Honda Fit that's 4.8ft side-to-side and 8.2ft front-to-back, for a footprint of 39sqft. Then you ask if it's a car or truck. This tells you which curve to use, and where along it to look.

Looking at the chart we can now see why it's hard for Honda to sell a Fit today. The best Honda could do for a five-seater non-hybrid hatchback is maybe a CAFE rating of 44mpg. [1] This puts them 23mpg short, and if Honda was a one-model car company they'd expect to owe $3,910/vehicle in fines: $17 per 0.1mpg shortfall. Since the regulation is about an average [...]

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First published:
May 24th, 2026

Source:
https://www.lesswrong.com/posts/7K8Bnn6Pwh5ciXpKR/taxing-small-cars-to-improve-mpg

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Narrated by TYPE III AUDIO.

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“Taxing Small Cars To Improve MPG” by jefftk

LessWrong (30+ Karma)

“Taxing Small Cars To Improve MPG” by jefftk