The cars can't stay here for more than a certain amount of time or your stay in Canada up to 2 years I believe. Transport Canada keeps pretty good tabs on whats around even at the diplomatic level. There will be a block on it when trying to transfer the ownership.. Its either ship it back to origin or scrap it locally. Then again stuff might fall through the cracks, not saying it doesn't happen but rare. There are lots of diplomat cars driving around that aren't sold here on regular plates or CD/CC . A good example, friends of ours are Irish Diplomats. They have been posted to Argentina, Mexico and Now NYC, their next positing will likely be Ottawa in 2 years. They have taken their personal car to all the postings, they are issued local plates. It's an MK5 Polo diesel... USA is being a bit annoying with the paper work though, its been stuck in Newark for a few months.