Tldr: Basically, it's just luck and which officer you end up with. Please try different border crossings at different times.
I bought a Toyota RAV4 in BC, Canada sometime back. I decided to move to Washington, US. I always assumed that the Canadian and US models should be pretty close but apparently not. I got the EPA compliance letter from Toyota, Canada. It explained that my car satisfies all the requirements except for the TPMS and some labelling. I called several registered importers but all of them hung up when I said the car doesn't have TPMS. I bought a $50 aftermarket TPMS from Amazon and got it installed by a mechanic for $70.
I drove to one border crossing between BC and WA. The officer looked at the paper work and was fine but then he came out to look at the TPMS modification and rejected it.
A couple of days later, I drove back to Canada and entered through a different border crossing late at night. The customs agent here looked at the TPMS invoice from the mechanic and was satisfied with it. He gave me the import certificate. I got a title from Washington State.
Basically, it's just luck and which officer you end up with. Please try different border crossings at different times. The documents you need are
1. Car purchase document
2. EPA compliance letter
3. Car registration in Canada
4. Insurance
5. KBB estimate of your car
6. Invoice from mechanic for TPMS installation
That's pretty much it. Good luck !!
PS: The labelling difference (Km/miles instead of miles/Km) is irrelevant.
