Comment by themaninthedark

I am not familiar with the NHTSA and EPA regulations to point you to one specfic place in the code but here is a citation. Also a lot of the Japanese vehicles that people point to as being more efficient are Kei class, these vehicles don't meet NHTSA code as they would not survive the crash tests.

https://gearshifters.org/nissan/how-to-import-a-nissan-silvi...

>Beginning in January 2024, the 1999 Nissan Silvia S15 will turn 25 years old. It will no longer be subject to NHTSA regulations after it turns 25 and can be legally imported into the USA.

>Because it did not adhere to federal safety and environmental regulations and featured a right-hand steering column, like cars in England, this particular vehicle was deemed unlawful in the United States. However, some Silvia vehicles have been registered in the US after being modified to comply with US laws.