[ponector]

>>> walk into a random local government office and hand them

That is exactly how it works. You go to the customs and hand them bunch of filled papers to proceed with customs clearance procedure.

Also you cannot simply import a car to USA, unless it is for a "demo" purposes or 25+ y.o.

[HarHarVeryFunny]

So where exactly? At the border? Someplace else?

If you were having a car shipped (literally) to you from overseas then presumably customs clearance is at the port.

What if someone buys a 1 year old car (any Brand, not just BYD) from Canada - what import fees would apply?

[ponector]

Custom clearance is at the customs office. At the border they will simply check the papers.

What fees to pay depends on the vehicle. Could be a chicken tax there as well

Also you simply cannot import for personal use a car which was not certified to be sold in USA.

[HarHarVeryFunny]

> Custom clearance is at the customs office. At the border they will simply check the papers.

Maybe you are not understanding the question.

Where is the customs office?

Do you get customs clearance first, then proceed to the border and show the paperwork?

Yes - I realize there are many cars the US does not allow, which is why I broadened the question to not just be about BYD.