I am assuming the question is specifically about bringing in the car from the US to Canada as part of one's immigration.

From my experience, when you are landing with a car as part of your initial move, you will not have to pay any taxes whatsoever.  You just need to mention as so to the Canadian Customs.  Mind you, some agents could be unaware of this rule and might proceed to charge you 15% tax on your car value, which can amount to thousands.  Politely but firmly, remind him/her of your entighteled allowance.  There should not be any problem as Canadian officers are much more nicer and professional than their US counterparts.

Once you are in Canada, you will have a month or so to get your papers in order - vehicle registration, license, insurance, etc.  You might need to make some minor adjustments to your US bought car, such as setting up day-time running lights, sticker on your speedometer making it clear that it is miles/hr dial, child seat harness anchor, etc.

Hope this helps.

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Recent conversation overheard at work:

American colleague, " Can't we just buy off Canada?"

Canadian colleague, "What... with your American Pesos?

Hey Thanks guys, esp. sqy.

No problem Captain - they typo was my fault anyway :) now that I look at the keyboard the "c" and "v" keys are next to each other. and to err is human anyway ;)